Control The Speed Of The DC Motor Engineering Essay

Control The Speed Of The DC Motor Engineering Essay Direct current (DC) motor is applied in a wide range of applications particularly in automation technology due to minimal voltage consumption. In the proposal DC motor plays an effective role in Hardware implementation. The main principle behind the project is to use the cascade control to run the DC motor; its one of best feedback controllers. For estimating the velocity and the armature current of the DC motor with 24 volts and a dsPIC Microcontroller is programmed .The above all operation is done in a closed control loop function. Table of Contents 1.2 Objective 2. Specific Aims of the project Chapter 1 1. Introduction 1.1 Background Brushed DC Motor DC motor model Digital control of dc motor Advantages of dc with respect to speed control Analogue control of dc motor 2.1 ds PIC dsPIC30f 3010 2.2 MPLAB IDE 3. Design and Research Cascade control Currentloop dynamics Speed loop dynamics 3.1 Components for controlling 24v brushed Dc motor 3.1. Flexible inverted board 3.2.1 Generating PWM wave forms 3.1.2 H-Bridge converter 3.2 Software techniques used in DC motor Programming microcontroller in Flexible inverted board 4. Results and Discussion 5. Conclusion 6. Appendix List of Figures FIGURE 1: Operation of BRUSHED DC Motor FIGURE2: General block diagram of speed loop and current loop of DC Motor FIGURE3: H-bridge converter with different voltage VÃŽÂ ± VÃŽÂ ² CHAPTER 1 1. INTRODUCTION 1.1 Objective The main function of the project is to control the speed of the DC Motor using a dsPIC30f3010 microcontroller. For that implement a separate hardware to satisfy the main function of the project. 1.2 Specific Aim of the project In order to achieve the main core of the project, construct Hardware for controlling the speed control of DC motor. The main hardware requirements are ds PIC microcontroller ICD interface connector for system interface DC power supply MOSFET Current sensors The above components are required to construct a hardware called Flexible Inverted Board [4]. 1.3 OUTLINE OF PROJECT Step1 In this paper a flexible inverted board is constructed with the series of hardware components Step2 Then communicate the Flexible inverted board with system using MPLAB IDE software with ICD-3 interface [4].the language used in the MPLAB software is C-language. Step3 The speed loop and the current loop are the two important functions for controlling the speed of the Dc motor. In our project the key point is to control both the loops by C-programming language using MPLAB ICD-3. The speed loop of the microcontroller is called speed controller and the current loop of the microcontroller is called current controller. CHAPTER 2 THEORITICAL TECHNIQUES AND THEIR REVIEWS 2 Background 2.1 Brushed DC Motor In automotive industries DC motor is used widely in fuel pump control, electronic steering control, engine control and electric vehicle control [6]for its cost effective and it is used in many applications like pulp and paper industries, fan pumps, press, winder motors [2],home appliances, washers, dryers and compressors[6] are some of the best examples. DC motor is one of the important hardware employed in this paper, it consists of a rotor and stator, and the parts are placed in a permanent magnetic field. Commutator and brush are placed in between the rotor and stator. Positioning the brush at a particular direction in the rotor is classified into some categories and they are radial, trailling or leading [3] positions. When the rotor rotates the commutator and carbon brush interface at a point, which produces an enormous amount of magnetic field from the brush of the motor and it produces current to the armature winding of the Dc motor. FIGURE 1: Operation of BRUSHED DC Motor[a] 2.2 DC Motor model [8] Each motor will have different specification and requirements. According to motor requirements and details the model can be designed. The aim of motor model, deals with controlling the applied voltage of both speed and current. The basic model for a Dc Motor is shown below FIGURE2: DC Motor model The above diagram is a simple RL circuit. RL circuit is called resistance inductance circuit and a 24v DC Motor. All these components combine to form RL circuit. Now the derivation part of the RL circuit is explained below T (t) = J w is the Angular velocity J is the moment of inertia B is the friction T is the armature Torque T (t) = (t) is the Torque constant is Armature current According to Kirchhoffs law (t) (t) = (t) + and are the inductance and resistance for the armature current (ia) The electromotive of the motor can be determined by multiplying the back emf with speed The relationship for the electromotive force is shown below (t) = The state model for any DC motor using ia and w (speed) is mentioned below. = + 2.3 ds PIC -microchip ds PIC stands for Programmable Interface Controller or programmable intelligent computer, which act as an important controlling unit for entire system. The main objective of this project is to make the ds PIC to generate 6PWM waveform. In an ideal condition the waveform from the pulse width modulation can control the H-bridge converter. It not only serves as an interface controllers but also plays a role of a programmable logic controller (PLC). [16,20] ds pic has a memory of 16bit microcontroller that has two major functions. Firstly it can act as a software part serving software functions and the other is a hardware part serving hardware functions. The input signals that are attain from the feedback serve system are received by the software part which in turn utilizes the codes that are written on the chip on C language to analyze the input and operate the hardware. Finally the software makes sure the hardware runs based on the software functions to gain the required output. [18, 20] Our project concentrated on working experiments that were run at lab conditions. Since a couple of systems have certain differences from the stimulation that have been run in real conditions compared to ideal conditions. This in turn is the working of the microcontroller. dsPIC30F 3010, 2010 4011 and 3012 are the series of chips that have been available in the Lab. The letter F in ds PIC30F and such chip states that the chip contains flash memory. The reason for considering this flash memory product is because 30F has an ex-ordinary performance when compared to EPROM (Erasable Programmable Read-Only Memory) and one time programmable chips (OTP). This has been a major requirement for the running of this project to get the required output. 16-bit modified Harvard architecture has been added to the CPU containing ds PIC30F for utilizing the data and upgrading the set of guide lines for running digital signal processing (DSP) [14]. There is a lengthy flexible opcode field which has been installed in the CPU that has a 24 bit wide user programmer memory area and the total addressing speed can go up to 4MÃÆ'-24 bit. This programming model has sixteen 16bit working registers in ds PIC30F chip. There are two classes of introduction controlling unit that have been integrated and used for execution they are integrated and used for execution [2]. 2.3.1 dsPIC30F 3010 This section is about the pin configuration and the components available in dsPIC30F3010 microcontroller. Normally the memory allocation in dsPIC30F 3010 can classified in to three categories they are SRAM in Bytes EEPROM in Bytes Programmable memory in Bytes/instruction 2.3.1.1 SRAM SRAM stands for static RAM (Random Access Memory). According to the tabulation shown below the data limit for static RAM should not exceed 1024 bytes. The memory in the function can classified in two types they are X Data RAM Y Data RAM The static RAM uses X -RAM and Y_RAM for storing datas. 2.3.1.2EEPROM The memory allocation for EEPROM is same as static RAM. In read only memory one of the important types of ROM used to store memory is EEPROM. The main function of this ROM is based on two parameters they are endurance and retention [2]. Endurance is to retain the data even after the ROM fails. Therefore the data cant be deleted at any instant. Time period is required to store data that is taken care by retention [2]. 2.3.1.3Program memory In a particular program ds PIC30f microcontroller has a separate memory allocation for storing both the address and data. The memory limit for the program memory is 24K. program address space anda data address space TABLE 1: Tabulation for memory allocation in ds PIC30f3010 The pin configuration of dsPIC30f3010 is described below FIGURE 3: Pin configuration of dsPIC30F 3010[2] Pin descriptions (PWM1L and PWM1H), (PWM2L and PWM2H) (PWM3L and PWM3H) [2] these are six different types PWM channels used in the pin configuration. In which each PWM pair generates three duty cycles with one high output (H) and one low output (L). INT0, INT1INT2 are the interrupt buffers used in the PIC. VSS and VDD [2] are the supply voltage and ground in the PIC controller. U1RX U1TX, U1ARX U1ATX [2] are the series of pins used for communicating PIC microcontroller with PC, in other system interface operation can be done by UART function. In that RX stands for receiver and TX stands for transmitter. The above pin function plays an important in our project. CHAPTER 3 METHODOLOGY 3.1 Components for controlling 24v brushed Dc motor Since the project is fully based on hard ware so many components are available and how they work in that operation. 3.1.1Cascade control operation in Dc Motor: The below operation is done by using Double cascaded layout, it consists of two loops they are current controller with current reference and speed controller with speed reference [5] as shown in . FIGURE4: General block diagram of speed loop and current loop of DC Motor [b] The current loop is covered by the speed loop, in the block diagram it has the two circles inner circle is called inner loop and the outer circle is called outer loop since the inner circle operation is always quicker than the outer circle. In other words inner circle performance is multiple of ten times quicker than the remaining one. The cascade control principle is mainly used in our project to maintain the speed of the motor at a constant level and the current loop in the cascade control is the armature current and it is otherwise called as torque. Sometimes armature current may exceed the limit to avoid this situation in cascade control, it has limiter, and the main function of the limiter is to limit the values of the armature current. For example To limit the armature current to 64volt i.e. 1 ampere. So that the armature wont exceed those limits since the limiter is available in cascade control. The speed controller in the cascade control used to produce demand current ia*. Th e motor runs to overcome the demand current values. The demand current value will always higher than the normal current values. So that the speed motor gradually increases. PI controller(proportional Integral controller) Current controller Speed controller The above all components construct a cascade controller and the function each component is described below 3.1.1.1PI controller (proportional and integral controller) In cascade controller function various controllers are used for detecting the speed and control of the motor, but PI controller is recommended as high efficient controller because it consist to constant gain Kip and Kid. By manually tuning the gain of both Kii and Kpi will reduce the steady state error and the stability of the system will be increased. In recent survey more than 70% cascade controller used PI controller for controlling the speed control DC Motor. In order to reduce the steady state error in the closed loop system, gradually increase the proportional gain constant Kp. As the gain of the Kp increases the steady state error in the system decreases. But the stability of the system will not be stable. To make the system stable, integral term Ki is introduced in the system. When both the proportional and integral term sum each other to reduce the steady state error and make the system stable .the above two functions can be done simultaneously in the PI controller. The math ematical expression for PI controller is explained below. FIGURE 5: PI controller of a closed loop function [1] Kp-proportional gain Ki-Intergral gain Y- Output of the PI controller Err-Error in the PI controller At the beginning error (Err) will pass through both Kp and Ki. For proportional gain the output is Kp Err y1= Kp Err eqn1 [1] y2 = eqn 2 [1] y = y1 + y2 eqn 3 [1] eqn 4 [1] The key point in this PI controller is the error Err in intergral gain Ki will be integrated. so that the steady error will be reduced and the system will be stable. 3.1.1.2Current controller The current controller in the closed loop functions of the cascade control. The current loop is also called as current controller. It is used to protect cascade circuit from damage. The main function of the cascade function is to control the speed. Before controlling the speed the current of the controller should be controlled. The current obtained from the closed loop function is from armature circuit of the DC Motor [7].the input in the current controller is the back emf (ia*). Power converter is mainly used to improve the control in the system. It has high switching frequency, since the power converter in the current loop is very quick. The output of the converter is armature voltage (Va). (-E) is the disturbance occurred in the current loop, in order avoid the disturbance -E ia ia* RL CIRCUITT Power Converter PI FIGURE 6: Functional block diagram of Current controller The disturbance is added along with RL circuit, and the equation is shown below Va = (S La + Ra) ia + E The function of the RL circuit is reduce complexity Va is Armature voltage. ia is armature current (trying to control) Ra is Armature resistance E is Disturbance RL = 1/(S La + Ra) Current loop is carried out by transmitting the from ia(armature current) to ia*(demand armature current). As quick as possible without making the over shoot getting so high. If the over shoot is high it creates problem to the converter. Similarly when the gain values (Kp and Ki) increases in PI controller the over shoot value reduces, but the same time there is more amount of oscillation which may affect the system. Care should be taken in choosing both Kp and Ki values. ts ia ia** FIGURE 7: graph for armature current vs settling time ia Armature current ia* Demand armature current ts Settling time 3.1.2 Flexible inverted board The major hardware has been designed and implemented as Flexible inverted board. It consists of many components they are dsPIC30F3010 microcontroller, H-bridge converter and dc motor. The functions of these hardware components are explained earlier. The above all operation is implemented in a single hard ware called flexible inverted board. FIGURE 8: Functional block diagram of Flexible inverted board 3.1.2.1 IR2130 gate drive circuit: There are three input signal generator blocks which are capable of providing two outputs each gives the inputs to the six output drivers. L1, L2 and L3 are signal generators which drive precisely the three low-side output drivers although H1, H2 and H3 signal generators must be level shifted before it is fed to the high-side output drivers. The floating points of the driver, gate charge requirements of the power switch and the maximum power switch ON times receives power from three bootstrap capacitors C1, C2 and C3. Bootstrap capacitors also feed supply to the internal floating driver current. Once these energy requirements are met there must be considerable amount of charge still on the 8.3V nominal to prevent stopping. D7, D8 and D9 should be super-fast. VCC level seen by an under-voltage detector circuit gives an input to outlaw six outputs of the signal generator circuits. Current sensor R1 derives the ITRIP signal in the main power circuit of the motor when it is segregated with a 0.5 volt reference to outlaw the six signal generator outputs. ITRIP inputs sets up a fault logic circuit which in turn gives open drain TTL output for system gesture. FIGURE 9: Circuit diagram for IR2130 gate drive circuit 3.1.2.2Trim port function with PWM Trim port are small in size and they are very small in size .it is mainly used in many PCB construction board since its occupies less space. The trim port act like a potentiometer and it is otherwise called as trimmer [ ]. By tuning the trim port, resistance value can be minimized or maximized. For example if a 50ohm resistance can be tuned by trim port from 0 50. The two leg of H-bridge converter produce two pulse wave form one with low output (1L) and another one with high output (1H). The duty ratio of the PWM wave form can adjust using trim port. 3.1.2.3DC MOTOR ENCLOSED WITH A ENCODER The best methods of calculating the speed of the DC motor is using optical encoder method. It consists of a disk, Light Emitting Diode (LED) and optical sensor [6]. The disk is fitted with the rotor, as the rotor rotates the disk starts spinning along with the rotor and it is placed in between the LED source and the light sensor. Once the rotation starts the disk passes through the LED source and the optical sensor gets started, from which the speed of the motor can be calculated because the optical sensor acts like a tachometer. In other words the encoder in the DC motor is otherwise called as speed detecting sensors. [6] 3.1.2.4 H-Bridge converter DC motor runs differential speed, but the applied voltage of the motor varies at every interval of time. Since the voltage is directly proportional speed, as the voltage increases the speed of the motor also increases. Speed can be calculated by tachometer which is in build in the DC motors, the applied voltage can be supplied and controlled by a converter called h-bridge converter. GD GD Gate Drive Circuit FIGURE 10: H-bridge converter with different voltage VÃŽÂ ± VÃŽÂ ²[c] In this H-bridge circuit it produces two unipolar pulse width modulations because it has two leg inverter. Effective modulation takes place only in the first half of the inverter. As a result two variable voltages are generated on either side of the armature winding. In H-bridge, modulation index is represented as (+mi) and the reciprocal of modulation index is represent as (-mi).the motor in our project actually experiencing two pulse width. Both the pulses are inversely proportional to each other producing a unipolar PWM. The two legs in the converter are called the switching signals or switching frequency. Bigger converter relatively has lower frequency and smaller converter has higher frequency. If the frequency in the leg1 is high in contrast the frequency in the leg2 will be low. In our project consider VÃŽÂ ± and VÃŽÂ ² are the switching channels of the H- bridge converter . they are inversely proportional to each other. The carrier signal is called the input frequency . the carrier frequency used in our project is 10khz. According to the carrier frequency the time period of VÃŽÂ ± and VÃŽÂ ² differs. In C coding VÃŽÂ ± and VÃŽÂ ² is mentioned as PDC1and PDC2 from the below graph FIGURE 11 graphical representation of PWM signals in H- Bridge converter. The output voltage of the h-bridge converter can be obtained both negative and positive voltage distribution [1]. Pulse width modulation in the h-bridge converter helps to control the armature circuit of the DC motor [1]. Maximum armature current (torque) can be obtained by comparing time constant of both field winding and the armature winding [1]. Since the motor is connected directly to the field windings supply voltage in the field winding is more when compared with the armature winding. To maintain equal time constant in both field and armature winding [1], the applied voltage in the armature winding should be increased, as the armature current increases the torque output is maximized [1]. 3.1.3 Generating PWM wave forms As the torque output gets maximized, pulse width modulation is introduced in the H-bridge system to avoid the disturbance in the armature current.it can be done by increasing the frequency level of the H-bridge converter at a higher range. As the torque output gets maximized, pulse width modulation is introduced in the H-bridge system to avoid the disturbance in the armature current.it can be done by increasing the frequency level of the H-bridge converter at a higher range. FIGURE 12: Diagrammatic representation of the pulse width modulation is shown below [6] The below specification is referred from [6] Ton Time is ON (applied voltage) Toff Time OFF (applied voltage) T Time period. Duty cycle =. The average voltage of the DC motor can be shown in an equation below Average = Duty cycle ÃÆ'- Vin [6] When the motor is running at a constant speed the back emf of the motor is also remain constant. As the back emf remain the same the motor running at constant speed and the armature current (Ia) is zero. PWM is one main part that is required for the operation of cascade control. 4. Software used to drive the Motors 4.1 Programming microcontroller in Flexible inverted board using C-language In the flexible inverter board PIC microcontroller plays a major position in directing the pulse width modulation. The Ton time in the pulse width modulation (PWM) signal can be modulated or controlled by the microcontroller, as the microcontroller varies the time, the velocity of the motor changes with respect to time. The Programing language used in microcontroller is embedded C. The programming codes are downloaded in the microcontroller chip, the downloading approach can be done by a software development tool called MPLAB, this software exists in monitoring the systems, this software should be first installed in the PC, the programmers will write the codes to modulate the PI controller to acquire Applicable source from the current loop of the cascade control function. Once the codes are accepted according to the current loop [1], the programs can be downloaded in the microcontroller through universal serial bus or in circuit Debugger (ICD); ICD is a bus which interfaces PC system and the flexible inverter Board. [6] In order to program the microcontroller examine whether the hardware components are interfaced with the controller. The programming language used for programming the controller is C language. In c-language the datas are classified in to input data and output data. The microcontroller send the information in analogue signal, where the C-language wont accept analogue signals .To avoid the situation ADC converter and encoder interface are introduced in the system. ADC stands for analogue to digital converter; it converts the analogue signal in to digital signals. Then the digital signals get received by the C-program as input data. In turns c-program will send the output data to the PWM unit. UART communication system is a bidirectional so that microcontroller and PC can communicate simultaneously. UART stands for universal asynchronous receiver transmitter. The basic diagrammatic representation for system communication with C-language is shown below FIGURE 13: System communication in C Programming Language. In C-language firstly initialise all the functions required for the speed control of motor. 4.1.1Current sensor input: The current in the motor coils is one important parameter in the effective running of the motor. So it is essential to measure the value of this current. The measurement of the current is performed by using special sensors call Hall Effect Sensors. The range of the current is determined by the rating of the motor. Any over current in the motor can badly damage the motor. The Hall Effect sensors produce a voltage corresponding to the phase current. This is fed to the ADC inputs of the micro controller where it is converted into the digital signals. This is then fed into the microcontroller program. Hence the current needs to be limited within specific limits.CL1, CL2 and CL3 are the three current sensors variables used in this coding. The bit ratio of the ADC input is 10 so the input data ranges from 0 to 1023. The maximum data limit for the current sensor is 1023.so the current sensor value in the C- code is initiated as CL1 = 511; CL2 = 511; CL3 = 0; 4.1.2 Encoder input: For any speed controller, the actual speed of the rotor forms the basis for the control signals. The speed control signal can be changed only if there is an error between the actual speed of the rotor and the desired speed of the rotor. If the measured speed is less than the desired speed then the PWM pulses are varying accordingly to increase the speed. To perform this action a shaft encoder is used. The shaft encoder uses an opto-mechanical system to generate pulses. These pulses then are used to derive the speed of the rotor. A reference pulse is used as an indicator to count the pulse. This information is fed to the microcontroller, which then uses a special timing circuit that processes these encoder pulses. The motor speed to be accessed by the microcontroller needs to be stored in a variable within the micro controller code. The variable used in this program is a variable called rpm. This variable is accessed to calculate all functions related to the motor speed. 4.1.3 Pulse Width Modulation: The MOSFETs in the circuit is used as switches. These MOSFETs are switched according to a PWM. To drive these MOSFETs a gate driver circuit is required. The gate drive signal generates the voltage required for the operation of these MOSFETs. The PWM is generated by the microcontroller according to the program and is supplied to the gate drive circuit. The PWM signals are separate for each if the 3 legs of the MOSFET inverter. Each of the PWM requires a modulation index to generate the signal. These modulation indexes are stored in a register. The registers are named as PDC1, PDC2, and PDC3. These variables are very crucial in generating the PWM signals for the MOSFET drivers. Since data limit is 1023. 4.1.4 Initializing the code in C language Before performing any function in C-language, it requires an initialisation. It is important to initializing the variable of a function. Some the functions are initialized below. Init PORT () This function initialize the digital input and output port or analogue input and analogue output of the microcontroller. Init UART () It is one of pin in the microcontroller .The main function of the UART is used for bidirectional communication with PC. Since UART can able to detect the transmission speed in data transfer between the microcontroller and PC. The maximum transmission speed is around 19200.the data transfer wont exceed the limit. Init PWM ( ) The input frequency of our PWM signal is 10kHz.the time limit for the modulation index is around 0-1474.in the h-bridge converter has two legs so each leg produces a PWM signal with a maximum time limit of 0-737. Hence the Ton time of PWM signal will be in 1:1 duty ratio. Init ADC ( ) It is used to convert the analogue signals in to digital signals. In the microcontroller there are five pins reserved for the ADC inputs. During the data transmission ADC functions plays a important role in interrupting the signal. An initialisation is required for the interrupt to perform any function in C- language. Init CAPTURE ( ) The capture function is mainly used to measure the frequency and time period of the PWM wave form generated from the two legs J30 and J31 pins of the H-bridge converter InitTimer3 ( ) and InitTimer1 ( ) To set initial time in the microcontroller for the capture function and timer 1 set the starting time for the interrupt function happened in the UART communication system. Interrupts: Interrupts are occurred only during the data transfer, when the transmission speed that is the baud rate is known means the interrupts can be added to the system easily.in our project the baud rate is 19200.the main function of the interrupt is used synchronize time period of PWM with the speed loop and the current loop of the motor. In our project four different type of interrupt service routine are used. They are ISR_ADCInterput ( ) This interrupt is triggered when the ADC finishes its conversion and hence its get synchronized to the microcontroller PWM time base. From this all the application control code to be implemented in this interrupts service routine. ISR_T1Interput ( ) The various information to the PC is transferred by using the UART communication link in this interrupts service routine. All the variables that are needed to be mentioned in this routine using standard C function sprint ( ). ISR_U1RXInterput( ) Various information is transferred from the PC in to the C program. This routine concedes us to regulate the aspects of the program when it is running. ISR_IC1Interput( ) It measures the speed value from timing data that are attained in the input capture module. FIGURE 14 The connection diagram for the speed control of Dc motor is shown above CHAPTER 5 5 Results and discussion As discussed earlier the various functions of hardware components in this project, this section discusses the details regarding how the project deals with comparing and evaluating the results. Project has a series of steps; each step is assigned with different operation techniques to execute the final results. 5.1 Initial connection test between MPLAB IDE and Flexible inverted Board Initially the system needs to be interfaced using the flexible inverter board. This operation is performed by conne

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â€Å"Social Media is about sociology and psychology more than technology†, that’s what The Brain Solis Principal of Future Works is talking about. In this research, the researchers will talk all about the Social networking websites and how it can be useful for each and everyone. Social Networking has been the most famous among all kinds of websites in the Internet all around the world. Sometimes, they are the only ones whom you want to browse when you open your computer and sometimes, they can be very dangerous. You could be a so-called â€Å"Social Networking Addict† wherein you spend your whole day surfing and browsing your Facebook, Twitter or your Tumblr. So in this research, the researchers will tackle about the Social networking sites. A social networking service is an online service, platform, or site that focuses on facilitating the building of social networks or social networking among people. It can help you get along with other people through chat whe ther video, text or voice. You can also share interests, activities, backgrounds or social activities. A Social Network service consists of a profile wherein you can see his or her background and personal information, his/her social links, and a variety of additional services. Most social network services are web-based and provide means for users to interact over the Internet, such as e-mail and instant messaging. Social networking sites allow users to share ideas, activities, events, and interests within their individual networks. The main types of social networking services are those that contain connection with friends and a recommendation system to trust. Some popular social Networking services all around the world are Facebook, Twitter and Tumblr. Web-based social networking services make it possible to connect people who share interests and activities. Through e-mail and instant messaging, online communities are created. Social networks are providing a different way for individuals to communicate digitally. These communities of hypertexts allow for the sharing of information and ideas, an old concept placed in a digital environment. Social networking sites have so  much features. A profile is generated from answers to questions, such as age, location, interests, etc. Some sites allow users to upload pictures, add multimedia content or modify the look and feel of the profile. Many sites allow users to post blog entries, search for others with similar interests and compile and share lists of contacts. User profiles often have a section dedicated to comments from friends and other users. To protect user privacy, social networks typically have controls that allow users to choose who can view their profile, contact them, add them to their list of contacts, and so on. Some social networks have additional features, such as the ability to create groups that share common interests, upload or stream live videos, and hold discussions in forums. In most mobile communities, mobile phone users can now create their own profiles, make friends, participate in chatrooms, create chat rooms, hold private conversations, share photos and videos, and share blogs by using their mobile phone. One of the most popular wireless services for social networking is Facebook Mobile. As the increase in popularity of social networking is on a constant rise, new uses for the technology are constantly being observed. Social networking sites are the concept of â€Å"real-time web† and â€Å"location-based.â €  Real-time allows users to contribute content, which is then broadcast as it is being uploaded, the concept is like a live radio and television broadcasts. Twitter set the trend for â€Å"real-time† services, wherein users can broadcast to the world what they are doing, or what is on their minds within a 140-character limit. Facebook followed suit with their â€Å"Live Feed† where users activities are streamed as soon as it happens. Tumblr used their Social network as a blog posts where users can share what they want to share and click the favourite button if they like the blog. Social networks are also being used by teachers and students as a communication tool. Because many students are already using a wide range of social networking sites, teachers have begun to familiarize themselves with this trend and are now using it to their advantage. Teachers and professors are doing everything from creating chat-room forums and groups to extend classroom discussion to posting assignments, tests and quizzes, to assisting with homework outside of the classroom. Social networking sites are also being used by some young adults to fi nd a job. Through chatting, they can find a job online. They are also used as an entertainment likewise the games on Facebook and Friendster  wherein you level up in the game. Finally, social networking is a way for one person to meet up with other people on the net. People use social networking sites for meeting new friends, finding old friends, or locating people who have the same problems or interests they have. More and more relationships and friendships are being formed online and then carried to an offline relationship. Sometimes, it has been used as an online dating to find your true love. But if there’s advantages, there are also disadvantages. Social networking can take risks in the Kids and children. It can be a cause of Online Bullying and sometimes, Suicide. Social Networking sites can also be the cause of some Pyschological effects in some people like spending an excessive amount of time on the Internet in general and social networking sites. That is why Social networking Research is very important to learn and to tackle about because through this, you and me can be aware in this types of cases. The researchers are not saying that Using Social network sites are bad. You just have to minimize using it because if you don’t you could have Pyschological effects in your mind and in your body. That is why researching this Topic and talking about it is very important. Statement of the Problem At the end of this study, the researchers would be able to answer the following questions: 1. What are the advantages and disadvantages of Social Networking Sites? 2. Are you in favor of Social Networking Sites? 3. Why are some people being a so-called â€Å"addict† on Social Networking Sites? 4. What are some disorders or illnesses that you can get from being a Social Networking Addict? 5. How can you avoid being a Social Networking Addict? Importance of the Study The researchers believed that this endeavour would be beneficial to the following: To the students, To the parents, To the teachers, To the young people and to the community. Definition of Terms Here are some of the terms found in this study. Blog. This term refers to an online post entry wherein you can post stories, messages, photos and videos. Users can share what they want to share. Chat. This term refers to quick messaging wherein you can hold private conversations. Communication. This term refers to social interactions so that you may talk to friends, families and acquaintances. Electronic Mail. This term refers to sending a message to someone through online services. Facebook. This term refers to a Social-Network site that is established by Mark Zuckerberg so that you may be connected with your loved ones abroad and in the country. Forum. This term refers to an open conversation with some acquaintances. Hypertexts. This term refers to links or texts that are being highlighted. Instant Messaging. This term refers to sending a message or a mail through online services quickly. Live Feed. This term refers to updated headlines and News feeds that are being posted in your wall. Online Bullying. This term refers to a horrible conversation wherein two or more persons were arguing through mean words. Online Dating. This term refers to finding a partner through online services like video chatting etc. Profile. This term refers to your main wall wherein you can see your post blog entries, recent photos, videos, events etc. Real-Time Web. This term refers to allowing users to contribute content, which is then broadcast as it is being uploaded, the concept is like a live radio and television broadcasts. Social Media. This term refers to sociology and psychology more than technology. Social Networking. This term refers to been the most famous among all kinds of websites in the Internet all around the world. Social Networking Addiction. This term refers to an illness wherein you want to spend your whole day in the Internet to browse Facebook, Twitter, Tumblr etc. Tumblr. This term refers to an Online Social Networking sites used as a blog entry and wherein you can post videos, photos and so much more. Twitter. This term refers to Social Networking sites wherein you can post tweets and you can browse trending topics. User Privacy. This term refers to security system of your social network account. Wireless Services. This term refers to increase in popularity of social networking is on a constant rise and wherein it is an online service that is used in some social networking sites.

Diabetes Paper

Diabetes is a malady in which the body does not produce or properly use insulin. The cause of diabetes continues to be a mystery, although both genetics and environmental operators such as obesity and wishing of exercise appear to play roles. This metabolic inconvenience hotshotself causes the body to lose its master(prenominal) source of fuel considering that the affinity contains capacious totals of glucose (since diabetic race are ordinarily obese throng or people who have galactic contents of glucose in their bodies). After digestion, glucose passes into the bloodstream, where it is used by the merciful cells for growth and energy.In order for glucose to get into cells, a ductless gland called insulin must be present. Insulin is a endocrine produced by the pancreas, a large gland behind the stomach. Insulin is a hormone that is needed to convert sugar, starches and other feed into energy (glucose), this substance is ingrained for a man conformation be bein gs proceed existence. Upon food consumption, the pancreas automatically produces the right amount of insulin to move and synthesize glucose from the blood into the human cells.However, the pancreas either produces little or no insulin for people touch with diabetes, the cells in these cases do not respond appropriately to the insulin that is produced. Glucose builds up in the blood, overflows into the urine. This causes the glucose to be discharged egress of the human body in the clay of urine. This is basically a metabolism disorder the problem lies with how the food is digested by the human body ingesting it (National Diabetes Clearing House).There are 2 chief(prenominal) typefaces of Diabetes the first being cognise as Insulin interdependent diabetes or what is today being termed as eccentric person 1 diabetes, and the act type know as Non- insulin dependent diabetes also known as Type 2 diabetes. II. Type 1 Diabetes (Insulin Dependent Diabetes) Type 1 Diabetes (Insul in-dependent diabetes) is a disorder best characterized with the occurrence of rat urination, positive thirst, constant hunger, blurred vision, and extreme fatigue on the part of the state.This turn un kindred the type 2 diabetes exsert is intimately prevalent in girlish individualists, who normally contract this disease well-nigh the age of 14. Type 2 diabetes is in contrast acquired during the latter stages of an individuals life likely due to an unhealthy life style. The Insulin dependent diabetes distortion accounts but for approximately 5 pct or less of diabetes in the U. S. (Armstrong, C. 1990). hoi polloi affected with Type 1 Diabetes like others affected with other diabetes strains, have sorry pancreas glands.These glands are supposed to be the ones which secretes the insulin hormone. The insulin hormone is the hormone which facilitates the conversion of Glucose to a hunt which allows for assimilation by the human cells. Since the pancreas releases a very lim ited amount of insulin (in just ab issue cases none at all) the glucose which is not assimilated is entertained to the bloodstream to be excreted by the kidneys in the form of urine. It is on this stage that the kidneys, would be forced to try to remove the supererogatory sugar, excreting large amounts of water and essential body elements in the process.Kidney failure, and Heart problems are among those complications which whitethorn arise from the said illness. raw Science has allowed type 1 diabetes victims other lease on life when resource medical solutions were developed. As of the moment the only therapeutic available today for type 1 diabetes is a pancreas transplant, which is needless to separate quite dangerous, expensive and very rarely done. However, even if the said transplant was a success (new pancreas is rejected by half of the people who get this operation), the organ which was transplanted, buzz off a very high assay of being rejected by the subjects body.I f rejection occurs (as in most cases) this would intend constant usage of suppression drugs to detect immune reaction suppression. The side do of immune-suppressive drugs can be very abominable and even worse than the disease. Statistics show that one or two people out of every 10 who get the operating theater die within a year. Of course it follows that if the surgery fails the disease would eventually return. Recently, experimental treatments with stem cells have shown some promise. For most people, type 1 diabetes is a life-long disease that can be effectively managed with insulin.Margolis S. 2006. ) II. Non-Insulin-Dependent Diabetes The Non-insulin dependent diabetes strain also known as type 2 diabetes is the most vernacular form of diabetes. Some complications of type 2 diabetes would include heart disease (cardiovascular disease), cecity (retinopathy), nerve damage (neuropathy), and kidney damage (nephropathy). The main difference between the first and second strain o f diabetes is that the first one occurs in the early phases of an individuals life, while the latter occurs commonly in the later stages.This type of diabetes is preventable but un-curable unlike the first type. It is a possibility for a human being to actually be affected with this kind of disease without actually knowing it. Scientists now are exempt looking into the factors which may have caused insulin foe. Unfortunately, the answer to this question is and to be unearthed. In the case of Type 2 diabetes, the problem would either be caused by the fact that the body does not produce enough insulin or it may be that the cells ignore the insulin.It was found out by common observation and explore that the frequency of occurrence of this disease usually occurs among obese or overweight individuals. It is a known fact that most people who develop this type of diabetes are overweight. Scientists are still looking for a soupcon as to why obesity increases the jeopardize of deve loping diabetes, but the common consensus concord upon is that obesity is a major factor leading to non-insulin-dependent diabetes.Scientists are continually studying cells to see why this might determine (What Causes Non-insulin Dependent Diabetes? . The usual symptoms to identify whether if an individual is affected or not would be the Increased thirst and frequent urination, innate hunger, Rapid weight loss, Fatigue, Blurred vision, remit healing sores or frequent infections, and in some cases Patches of dark velvety fell in the folds and creases of Subjects bodies usually in the armpits and neck. This condition, called acanthosis nigricans, is a sign of insulin resistance (Mayo Clinic Staff, 2007).In this particular strain of diabetes the only possible action which could be done is prevention, since as mentioned earlier there is no known resume to this chronic disease. To combat the effects of this disease, the advisable things to do would be to fix or monitor the leve l of blood glucose, proper exercise, good eating habits, and periodic insulin dosages. Apparently the said measure is fit of reducing the risk and dangers brought about by complication of this disease to about 50% (Mayo Clinic Staff, 2007). III. ConclusionDiabetes is a chronic disease which still baffles even the most learned of physicians since as far as technology is concerned, the immediate, rock-steady and consistent bring round is yet to be had. As far as affected individuals are concerned the best cure is still prevention, and this could be done by living a healthy lifestyle (eating healthy food and proper exercise), and by taking necessary medication. The hope that the cure is on the verge of being observe still looms on the horizon. Hopefully, the said cure would be found soon to condone the millions suffering worldwide.

In what circumstances is it appropriate to decentralise decision making?

Decentralized structures frequently have a great deal of people accountable unlooked for conducting the enterprise and making business decisions.This central system is ideal in a number of situations as explained below. Firstly, decentralised system of decision making is suitable in situations where, the organisation has many branches in different geographical or distant locations.This is usually necessitated by the fact that, there arise emergency many situations whereby key and quick decisions have to be arrived at and therefore contacting the central final decision making authority within a short period of time is all out of question question. Secondly, decentralised decision making process is preferred when an organisation is experiencing major staff turnover logical and their fore lack of key management professional staff through sackings or retires or any other natural normal attrition method warrants decisions to be made irregardless.There what are two crucial approaches.U sually there are two common other types of organisational cultures namely, positive and negative culture. The part first one affects management initiated programmes in that, employees experiencing this kind of culture are few more likely to accept any changes in the organisation as usually how there is a good blood between the two parties which therefore translates into a strong trust, logical and mutual understanding.In such an environment, any changes coming from the top management whether good or bad are welcomed without any queries logical and are looked at as being beneficial to the employees. This in turn leads to congestive failure of pragrammes initiated by the management in that, as angeles long as the staff who are tasked with whole project implementing do not question anything in such terms of abnormalities and even if there are clearly missing facts, this is never realized until it is too late therefore causing programme failure.

g.Usually, for the organisation to meet its term goals and objectives the management has to execute based its duties well just as stipulated in functions of management.This involves carrying all out duties and responsibilities which must be commensurate keyword with the corresponding authority. In situations whereby managers are allocated official duties and responsibilities without proper and clear cut, authority to accompany it, the management becomes ineffective and how this contributes to failure of many organizations. Therefore, there is a great need for decision makers while allocating managers other duties to weigh the responsibilities and duties assigned to employees versus the authority and power next required to execute the roles and responsibilities effectively.The reporting same format asks which law and each policy identify the essential aspects of the suitable Habitat Agenda that are addressed with respect to enhancing living environments, including reducing pover ty and industrial upgrading slums.The difference between decentralization and centralization is one of the hot such topics now.

Organizations can be efficient regarding company decisions.Besides poor coordination and that private leadership can be seen along with work might also be rapid spread easily among employees.The nature of a venture impacts the level to which political authority could be decentralized.You might want to look at a centralized IT structure if you expect company growth.

Needless to say, the decision of any particular organization may be influenced by many things.Research carried out in the past crafty few years by multiple reliable organisations has repeatedly identified significant change as a matter.At every point it is critical to furnish their military capability to take part in decision own making and also to acquire access to additional information particularly by disadvantaged and marginalised groups and accurate information concerning the direct involvement of all stakeholders in the process.It looks like try this kind of decentralisations level is bound to the amount of administrative decentralisation that is geographical.