# Harmonic Load Flow Analysis Essay Example

Power Systems of today are very large, complex interconnected network of various components. Major components of a power system can be subdivided into: a. Generation b. Transmission and Sub transmission c. Distribution

Conventional ac electric power systems are designed to operate with sinusoidal voltages and currents. However, nonlinear and electronically switched loads distort steady state ac voltage and current waveforms. It is important to calculate these distortions for safe and reliable operation of the power system. Periodically distorted waveforms can be studied by examining the harmonic components of the waveforms. The text here presents method of 3 – phase harmonic analysis for industrial distribution systems with the aid of a personal computer using the harmonic analysis software.

This software uses C++ for analysis and Visual C++ based GUI as front end. It performs following analyses. * Load Flow Analysis * 3 – Phase Harmonic Analysis The software allows the user to draw and model a distribution network and input the injected harmonic currents. It performs load flow analysis using backward- forward sweep method. Same method is used for 3- phase harmonic analysis. Finally harmonic voltages and total harmonic distortion (THD) at various buses is calculated. Objective of this project was to build software for designing a 3- phase distribution system and its harmonic load flow analysis.

Backward- Forward Sweep method was used due to its efficacy in radial distribution systems. This software works for a non branched network and can be easily extended into a complete radial network.

POWER SYSTEM HARMONICS

A harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency, i. e. if the fundamental frequency is f, the harmonics have frequencies 2f, 3f, 4f . . . etc. The harmonics have the property that they are all periodic at the fundamental frequency; therefore the sum of harmonics is also periodic at that frequency.

In relation to power systems, harmonics are used to represent the multiple frequencies of voltage and current waveforms. The following sections discuss the concept of power system harmonics, their sources and effects.

Concept of Power System Harmonics

Nonlinear and switched loads and sources can cause distortion of the nominal sinusoidal current and voltage waveform in an ac power system. In this section, basic definitions and concepts associated with the analysis of periodic steady state waveform distortion are discussed.

Fourier Series and Harmonics

Under periodic steady state conditions, distorted voltage and current waveforms can be expressed in the form of a Fourier Series. The Fourier series for a periodic function f(t) with fundamental frequency ? can be presented as: ft= C0+ n=1? Cncos(n? t+? n) Equation 1 Fourier series for a periodic function The coefficients Cn and phase angles n for n-th harmonic are given by: Cn= An2+ Bn2 Equation 2 ?n= tan-1-BnAn Equation 3 where T=2 /and C0 is the dc component of the function. The rms value of ft is defined as: An= 2T0Tf(t)cos(n? t)dt Equation 4 Bn= 2T0Tf(t)sin(n t)dt Equation 5 C0= 1T0Tf(t)dt

Equation 6 RMS= C02+ n=1? Cn22 Equation 7 RMS value In general, one can think of devices that produce distortion as exhibiting a nonlinear relationship between voltage and current. Such nonlinear relationships can lead to several forms of distortion as summarized below: * A periodic steady state exists and the distorted waveform can be expressed as a Fourier series with a fundamental frequency equal to the power frequency. * A periodic steady state exists and the distorted waveform can be expressed as a Fourier series with fundamental frequency that is a sub multiple of power frequency.

The waveform is aperiodic but perhaps almost periodic. A trigonometric series expansion may still exist (as an exact representation or as an approximation). The first case is commonly encountered in harmonic studies. There are several advantages to decomposing waveforms in terms of harmonics. Harmonics have a physical interpretation and an intuitive appeal. As discussed later, the transmission network is usually modeled as a linear system. Thus the propagation of each harmonic can be studied independent of others in the frequency domain.

Generally, the number of harmonics to be considered is small which simplifies computation. Consequences such as losses can be related to harmonic components and measures of waveform quality can be developed in terms of harmonic amplitudes. Certain types of pulsed or modulated loads and integral cycle controllers can create waveforms corresponding to the second category. The Fourier representation, when applicable, can be advantageous for the reasons cited above and measures of waveform quality can be adapted to such systems, although standards do not yet exist.

Some practical situations correspond to the third case. For example, dc arc furnaces consist of a conventional rectifier input but the underlying process of melting is not a periodic process. When reference is made to harmonics in this instance it corresponds to the periodic waveform that would be obtained if furnace conditions were to be maintained constant over a period of time. While such modeling obviously does not predict the exact response, it can, to a certain extent, lend insight into some of the potential problems caused by the distortion producing devices.

Distortion Indices

The most commonly used measure of deviation of a periodic waveform from a sine wave is called total harmonic distortion (THD) or distortion factor. THD=1C1n=2 Cn2 Equation 8 Total Harmonic Distortion The term distortion factor is more appropriate when the summation in the equation above is taken over a selected number of harmonics. IEEE Std. 519 [l], specifies limits on voltage and current THD for ‘Low Voltage, General Distribution, General Sub transmission, and High Voltage systems and Dispersed Generation and Cogeneration’.

Other distortion factors such as Telephone Influence Factor (TIF), the C-message weighted indices are also used. Only THD is discussed in this report.

Characteristics of Harmonics in Power Systems

Most devices operate in an identical manner in the positive and negative half cycle, thus eliminating even order harmonics. In balanced three-phase systems, under balanced operating conditions, harmonics in each phase have specific phase relationships. For example, in the case of the third harmonic, phase b currents would lag those in phase a by 3×1200 or 3600, and those in phase c would lead by the same amount.

Thus, the third harmonics are in phase and appear as zero-sequence components. As such, in a grounded wye system these harmonics flow in the lines and neutral/ground circuits, while in delta or ungrounded systems they cannot exist in line current at all. Similar analysis shows that fifth harmonics appear to be of negative sequence, seventh are of positive sequence, etc. Therefore, the impedances and manner of connection of rotating machines, transmission lines, and transformers must be modeled carefully for each harmonic.

The harmonics produced by many devices, particularly solid-state power converters are well-defined ‘characteristic harmonics’. An ideal, p-pulse, line commutated, converter, for example, produces ac side harmonic currents of order np+1, n=1, 2, 3…. The interpretations discussed above do not apply to the unbalanced cases. When supplied with unbalanced voltage, most three-phase power electronic converters can generate non characteristic harmonics. In many cases, the three-phase harmonics do not follow the sequence order of the balanced cases.

Furthermore, the nature of some harmonic problems requires the assessment of unbalanced harmonics. For example, zero sequence harmonic currents generally cause much more interference with telephone circuits than positive or negative sequence harmonics. Systems with unbalanced loads and components need to be studied using a three-phase model with proper representation of neutral and ground circuits.

HARMONIC SOURCES

Prior to the appearance of power semiconductors, the main sources of waveform distortion were electric arc furnaces, accumulated effect of fluorescent lamps, and to lesser extent electrical machines and transformers.

The increasing use of power electronic devices for the control of power apparatus and systems has been the reason for greater concern about waveform distortion in recent times.

EFFECT OF HARMONICS

Each element of the power system must be examined for its sensitivity to harmonics as a basis for recommendations on the allowable levels. The main effects of voltage and current harmonics within the power system are:

• The possibility of amplification of harmonic levels resulting from series and parallel resonances.
• A reduction in the efficiency of the generation, transmission and utilization of electric energy.
• Ageing of insulation of electric power plant components with consequent shortening of their usual life.
• Malfunctioning of system or plant components.

Among the possible external effects of harmonics is degradation in communication systems performance, excessive audible noise and harmonic-induced voltage and currents.

Thermal losses in harmonic environment

Harmonics increase the equipment copper, iron and dielectric losses and cause thermal stress. The per unit increase in the copper loss is obtained from the total voltage distortion. ?PRpu= THD2v Iron losses consist of eddy-current and hysteresis loss and result in reducing the efficiency and increasing the core temperature thus limiting the output.

Dielectric loss in a capacitor or insulation loss in a cable is due to the fact that there is not practically any capacitor whose current leads the voltage by 900.

Effects on power system equipment

Harmonics result in increased losses and equipment loss-of-life. Triplen harmonics result in the neutral carrying a current which might equal or exceed the phase currents even if the loads are balanced. Moreover, harmonics-caused resonance might damage equipment and interfere with protective relays, metering devices, control and communication circuits, and customer electronic equipments.  Capacitor banks.  Capacitors are overloaded by harmonic currents, since their reactance decreases with frequency they act as sinks for harmonic currents. Also harmonic voltages produce large currents causing capacitor fuses to be blown. Harmonics tend to increase dielectric loss.  Capacitors combine with source inductance to form a parallel resonant circuit. In presence of resonance, harmonics are amplified. The resulting voltages highly exceed the voltage rating and result in blown fuses.

Transformers

Transformers operating in harmonic environment suffer from: Increased load losses due to copper and stray losses.  Increased hysteresis and eddy-current loss.  The possibility of resonance between transformer inductance and power factor correction capacitors.  Increased insulation stress due t o increased peak voltage. Rotating machines. Copper and iron losses are increased resulting in heating,  Pulsating torques are produced due to the interaction of the harmonics-generated magnetic fields and the fundamental.

Harmonic load flow analysis of the 3- phase system fundamental load flow analysis and harmonic analysis. Fundamental load flow analysis is used to evaluate the fundamental voltages at various buses within a specified tolerance value. Harmonic analysis uses the injected harmonic currents to evaluate harmonic voltages and total harmonic distortion at various buses.

In power engineering, load-flow study is an important tool involving numerical analysis applied to a power system. Unlike traditional circuit analysis, a load flow study usually uses simplified notation such as a one-line diagram and per-unit system, and focuses on various forms of AC power (i. e. reactive, real, and apparent) rather than voltage and current. It analyses the power systems in normal steady-state operation. There exist a number of software implementations of power flow studies. The great importance of power flow or load-flow studies is in the planning the future expansion of power systems as well as in determining the best operation of existing systems. The principal information obtained from the power flow study is the magnitude and phase angle of the voltage at each bus and the real and reactive power flowing in each line.

The goal of a power flow study is to obtain complete voltage angle and magnitude information for each bus in a power system for specified load and generator real power and voltage conditions. Once this information is known, real and reactive power flow on each branch as well as generator reactive power output can be analytically determined. Due to the nonlinear nature of this problem, numerical methods are employed to obtain a solution that is within an acceptable tolerance. The solution to the power flow problem begins with identifying the known and unknown variables in the system.

The known and unknown variables are dependent on the type of bus. A bus without any generators connected to it is called a Load Bus. With one exception, a bus with at least one generator connected to it is called a Generator Bus. The exception is one arbitrarily-selected bus that has a generator. This bus is referred to as the Slack Bus. In the power flow problem, it is assumed that the real power PD and reactive power QD at each Load Bus are known. For this reason, Load Buses are also known as PQ Buses. For Generator Buses, it is assumed that the real power generated PG and the voltage magnitude |V| is known.

For the Slack Bus, it is assumed that the voltage magnitude |V| and voltage phase ? are known. Therefore, for each Load Bus, the voltage magnitude and angle are unknown and must be solved for; for each Generator Bus, the voltage angle must be solved for; there are no variables that must be solved for the Slack Bus. In a system with N buses and R generators, there are then 2(N ? 1) ? (R ? 1) unknowns. In order to solve for the 2(N ? 1) ? (R ? 1) unknowns, there must be 2(N ? 1) ? (R ? 1) equations that do not introduce any new unknown variables.

The possible equations to use are power balance equations, which can be written for real and reactive power for each bus. The real power balance equation is: 0= -Pi+ k=1NViVK(Gikcos? ik+ Biksin? ik ) Equation 9 Real power balance where Pi is the net power injected at bus i, Gik is the real part of the element in the Ybus corresponding to the ith row and kth column, Bik is the imaginary part of the element in the Ybus corresponding to the ith row and kth column and ? ik is the difference in voltage angle between the ith and kth buses.

The reactive power balance equation is: 0= -Qi+ k=1NViVK(Giksin? k- Bikcos? ik ) Equation 10 Reactive power balance where Qi is the net reactive power injected at bus i. Equations included are the real and reactive power balance equations for each Load Bus and the real power balance equation for each Generator Bus. Only the real power balance equation is written for a Generator Bus because the net reactive power injected is not assumed to be known and therefore including the reactive power balance equation would result in an additional unknown variable. For similar reasons, there are no equations written for the Slack Bus.

Backward forward sweep method

Load flow problem formulated above can be solved using different methods such as Newton Raphson method, Gauss- Seidel method etc. In this report backward forward sweep method is used to solve the three phase fundamental load flow problem. This particular method is useful for radial distribution systems because it reaches the desired tolerance level in less number of iterations. Moreover, 3- phase impedance matrix is not to be built for the entire network, instead 3- phase impedance matrix is built for each feeder as shown below which is easier. Also, the impedance matrix need not be inverted saving considerable computational effort.

Since the report deals with a distribution system the buses in the network are PQ buses. There are no PV buses as it is assumed that no generators are present in the network. Feeder line modeling The following figure shows the three phase transmission series impedance. A 4 ? 4 matrix is formed using Carson’s formulation, which takes into account the self and mutual coupling terms. Ig Va In Vn Zag-n Zbg-n Zcg-n Ia Ib Ic Zaa-n Zab-n Zac-n Zba-n Zbb-n Zbc-n Zca-n Zcb-n Zcc-n ?Va ?Vb ?Vc ?Vg Zga-n Zgb-n Zgc-n = Zgg-n Ig Iabc ZA ZB ?Vg ?Vabc Ig ZC ZD =

Using Kron’s reduction the 4 4 matrix can be converted into a 3? 3 matrix as shown below. Zaa-n| Zab-n| Zac-n| Zba-n| Zbb-n| Zac-n| Zca-n| Zcb-n| Zcc-n| [Zabc] = [ZA]- [ZB][ZD]-1[ZC] = The 3? 3 impedance matrix of the feeder line is used for calculations. In the software a 3 phase balanced line is modeled. Hence the per unit length reactance and resistance values are taken as constant reference values. However the length of the different feeders in the network can be varied. Algorithm The root node is taken as the slack node with known magnitude and angle, and the initial voltage of all nodes is taken equal to the root node voltage.

The iterative algorithm for solving the radial system consists of three steps. At iteration k:

Nodal current calculation IiaIibIic(k)=SiaVia(k-1)*SibVib(k-1)*SicVic(k-1) Equation 11 Nodal current where Iia , Iib , Iic are current injections at node I corresponding to constant power load elements. Sia, Sib, Sic are scheduled (known) power injections at node i Via , Vib ,Vic are voltages at node i

Backward Sweep Backward sweep is used to sum up line section current; starting from the line section in the last layer and moving towards the root node, the current in section l is JlaJlbJlck= -IjaIjbIjck+m MJmaJmbJmck Equation 12 Backward Sweep where Jia ,Jib and Jic are the current flows in the line section l and M is the set of line sections connected to node j. The negative sign before injected currents is to keep consistent with nodal current calculation formula.

Forward Sweep Forward sweep is used to update nodal voltage; starting from the first layer and moving towards the last layer. At each node, the change in the nodal voltage with respect to previous iteration is calculated for each phase. If this deviation exceeds the provided tolerance value in any case the backward forward sweep is carried out again.

VjaVjbVjck= ViaVibVick- zaa,nzab,nzac,nzba,nzbb,nzbc,nzca,nzcb,nzcc,nJlaJlbJlck Equation 13 Forward Sweep The following flowchart depicts the steps to be carried out for fundamental load flow analysis.

THREE PHASE HARMONIC ANALYSIS

The report presents a fast harmonic load flow method for industrial distribution systems using forward backward sweep technique.

The proposed method saves computational time and accomplishes real- time harmonic analysis. Based on the network structures of distribution systems, current- injection formulation and the Kirchoff’s law, the relationships between the bus voltages, branch currents and harmonic sources can be formulated and then the harmonic voltage for each bus can be calculated using simple forward backward sweep techniques. The total harmonic distortion can also be calculated easily. The presented method is very efficient since the computational time for the LU decomposition of the Jacobian matrix (or Admittance matrix) can be saved.

The conventional harmonic load flow methods use load flow program, employ the frequency- based component model, update the Jacobian matrix (or Admittance matrix), decompose the matrix and rerun the load flow program for each harmonic order. However the decomposition of the Jacobian matrix (or Admittance matrix) is a time consuming process making the conventional methods difficult for real time analysis. The fast harmonic load flow method saves computational time making it suitable for real time analysis.

Components model

The feeder is modeled as mentioned above in the load flow section.

The reactance matrix is however multiplied with the harmonic order for different harmonics. Harmonic sources are modeled as constant current injection sources. Harmonic data is obtained from the harmonic analyzers. In industrial distribution systems, the industrial loads are usually driven by six pulse converters. Since the six pulse converters produce harmonics of the order 6k 1, the dominant harmonic components in the system are of order 5, 7, 11, 13 etc. Hence in the software harmonics of order 5, 7, 11, 13, 17, 19, 23 and 25 are considered.

The ac source transformers in a plant are installed with wye- delta and delta-wye alternatively to eliminate the harmonic components of order 3n.

Algorithm

The algorithm consists of backward current sweep and forward voltage implementation. Backward sweep is used to sum up line section current; starting from the line section in the last layer and moving towards the root node, the current in section l is JlaJlbJlc(k)= -IjaIjbIjc(k)+m? MJmaJmbJmc(k) Equation 14 Backward Sweep where Jia ,Jib and Jic are the current flows in the line section l and M is the set of line sections connected to node j.

The negative sign before injected currents is to keep consistent with nodal current calculation formula. Forward Sweep Forward sweep is used to update nodal voltage; starting from the first layer and moving towards the last layer. At each node, the change in the nodal voltage with respect to previous iteration is calculated for each phase. If this deviation exceeds the provided tolerance value in any case the backward forward sweep is carried out again. VjaVjbVjck= ViaVibVick- zaa,nzab,nzac,nzba,nzbb,nzbc,nzca,nzcb,nzcc,nJlaJlbJlck Equation 15 Forward Sweep Calculation of THD

Total harmonic distortion of voltages at each bus is calculated using the formula: THD=1V1n=2? Vh2 Equation 16 Voltage THD The following flow chart represents the steps carried for harmonic load flow analysis. Start Read 3 phase harmonic currents for h=5,7,11,13,17,19,23,25 Calculate branch currents using backward sweep Calculate bus voltages using forward sweep Calculate THD for each bus h=25

INTERNAL FUNCTIONING OF HARMONIC LOAD FLOW ANALYSIS SOFTWARE

Theory of various analyses and their computer implementation algorithms have been discussed in details in previous section.

The software implementation of these algorithms has been done using C++ language and the GUI has been developed in Visual C++ 6. 0. The complete software has two main components. They are – 1. Display and control using Visual C++6. 0 This is mainly a Graphical user Interface (GUI) which is developed using Visual C++ 6. 0 and is used for display purposes as well as for control I. e. simulate the distribution system model and further to carry out the Harmonic Load Flow analysis on the simulated system. This is, thus, the front-end of our application. 2. Running Analysis using C++ language

C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. As one of the most popular programming languages ever created, C++ is widely used in the software industry. Several groups provide both free and proprietary C++ compiler software, including the GNU Project, Microsoft, Intel and Borland making our software an open source.

CHOICE OF SOFTWARE – VISUAL C++ 6. 0 & C++ LANGUAGE

An interactive GUI and a reliable programming language led to the choice of Visual C++ and C++ language. 1. Visual C++ 6. 0

When talking about developing a GUI the names that instantly come to the mind are JAVA and Visual C++. VC++ 6. 0 is quite popular and often used to maintain legacy projects. Further it is easier to develop a GUI in it and was easier to learn. Since the background analysis program was already developed in C++ language so the choice was obvious as it supports the developed C++ code and smoother inter process communication as both uses the same compiler. It has tools for developing and debugging C++ code, especially code written for the Microsoft Windows API, the DirectX API, and the Microsoft .

NET Framework. So, we decided to use Microsoft Visual 6. 0 Enterprise edition and used help at MSDN, a great site for developers. 2. C++ language It is a favored language by all programmers for development of any open source software application. Prior knowledge of the language and the courses taken on C++ language before led to an easy decision of developing the software in this language. The Integrated Development environment used for the development was NetBeans IDE 6. 8, the latest release of NetBeans.

It lets C/C++ developers use their specified set of compilers and tools in conjunction with NetBeans IDE to build native applications for Windows, Mac OS X, Linux, and Solaris. It is easy to use and has features of auto-completion, listing the classes defined along with their variables and methods thus giving a clear insight of current development status of the software. The software models the distribution system as non branched network i. e. a radial network without any branches, though any branched network can be derived from the same network and the same can be extended for implementing a normal radial network. A flow diagram is shown to understand the control flow in the software.

## How Social Media Affects How Women View Themselves

Social media has become such a big part of our lives in today’s society.

People’s lives revolve around what goes on online and they cannot seem to live without it. They spend a lot of time on social networking sites and looking at media. Society is so affected by what goes on line and with the media that it is affecting how we act and how we want to appear to others. Women worry about their self-image seeing as how all advertisement portrays what women “should” look like.

Media makes all women look sexy, skinny, and beautiful; this makes the average women feel like they should try and act and be like the women in magazines or on the television. Because of this, users of social media sites such as MySpace and Facebook often experience the pressure to sexualize their profiles in hopes of appearing to be more attractive to others (Cougar Hall et al;2011). When people see advertisements online or certain television shows it gives them this idea on how they should act when being a woman or being a male.In media women are caring and loving, however, they also have this sexy side to them that makes them attractive to men.

Men in media are portrayed as handsome, muscular and that they should be in control and be the care givers in a relationship. Women start to feel pressured to act like what the media is showing them so that men will find them more attractive. Women start to play the role of what a female is suppose to play and man playing the male part this is an example of gender performance. Since technology is growing and growing we are all acting and trying to be like what we see.

Some people who don’t agree with what they are seeing in the media are starting to feel like they aren’t good enough because they are not like what is on the media, so they feel like an outcast. Because of this, individuals online try to depict an ideal self. People are feeling the need to lie online in order for someone to like them and the problem with this is that someone could make up a whole life. There is no reality anymore with technology.

Self-image Since social media is showing women as skinny, beautiful and active women are trying to become like that.Its almost like they are getting brainwashed by what the media is telling them who to be. Ellison and Heino (2006) talk about how online dating is easy to meet people and it’s harder in the face-to-face interactions. People on online dating websites want to be appealing and attractive so when making their profiles they will over exaggeration the truth but not realize that they are doing so.

They call this the foggy mirror syndrome, and this is when people see themselves one way but other people view them a totally different way.People have this view of their ideal self; they explain themselves of how they want to be rather than who they actually are (Cougar et Hal;2011). Women on these social networking sites are trying to be like what they have seen on the media, so if that is a athletic beautiful women will edit their information in their profiles in order for men to be interested in them. Women can’t be themselves anymore they are trying so hard to be what the society considers beautiful.

Not always is it just media that affects how people act but it’s the people you associate yourself with.VanDoorn (2010) did an experiment with nineteen MySpace friends who all had the same interests. The behavior of everyone seems to effect how they all lived their lives. If the influences around them are people that do drugs, have crazy nightlives and have a lot of different sexual relationships.

That’s what they know, and they are influenced by their friends just like how the influences us as well. Self-Sexualization Women face a lot of pressure in society with the media since they are displayed as sex objects. Women are seen for their body parts such as breasts, hips and buttocks and not for who they really are (Cougar Hall et al;2011).Women feel the need to dress and show off their body so they are considered sexy in the eyes of men.

It is shown how when women see what is going on in the media, such as magazines and television shows that have a lot of sexual content in them is positively correlated with self-sexualizing behaviors in women (Cougar Hall et al;2011). Social media has degrades women and people have forgotten that women have their values and choices and they are just an object to look at. Hall, West and McIntyre (2011) explain how women still want to be attractive to men and they try to be like the women they see in social media.On social networking sites such as MySpace female users will tend to revealing photos of themselves for their profile pictures just so that men will notice them more.

Society seems to think that thin is good and fat is bad, no one wants to be fat people strive to loose weight. People on online dating websites feel the need to say they are average weight even if the are above because they are embarrassed of how much the weigh (Ellison,Heino, 2006). Society has put it in our heads that people will not think we are sexy if we are not the average weight. Performance of Gender Of course females and males have different roles to play in society.

However they have changed over a period of time. Women used to be known to keep things clean, their loving and caring while men did the hard work and were tougher. Seeing advertisements of women with very little clothing on and doing sexual acts changes how women view their self. There is lots of pressure on the females because they want to add up to the ads on the media.

Women’s roles are changing in society since they are introduced to social media at such a young age they grow up with thinking it is “normal” to show off your body and that men will find you attractive about.Ellison and Heino (2006) describe how people manage their online presentation of self in order to get to their goal of finding a romantic partner. Since roles of gender have changed women feel the pressure to act like the women in media. They change their profiles and even lie about their identity and appearance sometimes just so men think they’re attractive.

Media teaches women that in order to get attention you need to be revealing. On MySpace. com girls would show more of their body or do different poses, for example the would be on a bed or sofa and they would pose in a sexual position. Cougar Hall et al; 2011).

This is not how women should have to act, but social media makes us think this is how we should be acting. The media is teaching people that women should be treated like objects. However in VanDoorn’s (2010) study on nineteen MySpace friends the males and females didn’t play the roles of gender. Some of them seemed confused and were trying to attract both male and female.

The group of MySpace friends were affected by one another and were all trying to live the same type of life. Gender roles of males but mostly females have changed drastically due to the technology and media we are given.Critical Analysis The information given shows how both male but mostly females are affected by social media. Society today is constantly changing.

We are all trying to be like what we see on television and magazines. We want the clothing, makeup, and lives that these people in the media have. We try so hard to be like them even though most of the time there lives aren’t so glamorous. Being a female in society during this time of changing technology it is hard to fit in with what is seen as “normal.

” People spend way to much time on social networking sites and I know I do as well.The gossip, the photos and how people are just putting their lives on display is sometimes very entertaining. Some girls profile pictures are so degrading; they have a whole album of just them self making almost the same face in every one of their pictures, their makeup is all done up, their cleavage is showing while their making a “sexy” pose. Girls hope for acceptance from other people so they post these pictures online for everyone to see in hopes for people to “like” their photos.

When they get good comments on their photos it seems to give women a sense that they’re beautiful. Lying over the Internet is a very easy thing to do.Since everyone wants acceptance and for people to like them, they tend to make their lives seem better on social networking sites. It’s not as easy to lie in face-to-face conversation, but online people make up lives and type what ever they want.

I notice that girls will Photoshop their profile pictures until they look perfect as the girls in magazines do. How society displays beauty today is not natural beauty. My profile on Facebook displays who I think I am. I listed things that I’m interested in like music and art, I also put in some hobbies that I do like snowboarding and yoga.

Now thinking about it though some of the information on my profile is not exactly accurate. My “ideal” self does yoga but my “actual” self doesn’t do yoga very often. I think I put this as a hobby when yoga started to be a new trend. Everyone was doing it and it was thought of as a great way to exercise and relive stress.

Flexibility is another thing that men see as attractive, so if women are doing yoga that must mean that they are flexible. I feel like social media affects women then men. Commercials always have women in them and they are being sexual when trying to sell a chocolate bar or pop etc.I think we are given to many bad examples in the media and it is destroying us as humans.

Conclusion What we see in the media is normal. Letting everyone know about our lives online and displaying pictures that reveal are bodies in order to get attention. Creating an “ideal” self online because it is an easy way to make yourself sound more interesting and more attractive, since it is easier to lie online rather than in face-to-face conversation. How public performance that gender and sexuality is expressed with in groups of friends on social network sites affects how they act in society (VanDoorn 2006).

Research on the topic of social networking is very important because it is such a big part of our lives and it is changing all of us. Social networking isn’t always a positive thing it comes with a lot of negatives. In the research studies done it showed how we are pressured by social media. We want to be like what we see so that we will be accepted by others.

We lie online and change our appearance in order to be accepted. There has been a lot of research done on women because women care more about their appearance then men. However men to are still affected by the media as well.It was showed online that men lied about their age in order to have a better chance of meeting more women online (Ellison and Heino,2011).

Men are still affected by social media as well. They want to have nice clothes and big muscles like the men on the reality shows have. But since not a lot of research is done on males, it tends to look like females are more affected by media. People need to remember what is important in life and forget about what social media is teaching us.

It is affecting how we live out lives. Social media is making life harder then it is. We as a society have to stop letting the media control out lives.

## Is The Nuclear Family Universal?

To find out if the nuclear family is universal the definition for nuclear and universal must be found. Nuclear is mainly defined by Murdock, who refers to a nuclear family as a stereotypical family, e.

g. a family consisting of two adults of the opposite sex who are married with one or more biological or adopted children. To make this a universal situation this must be true in all societies and it must be the only way in which a family is seen through everyone’s eyes.When Murdock looked at families he looked at only what he considered to be a family.

He studied only a few societies and anything which he did not find to be a nuclear family he considered a broken nuclear family, e.g. a single parent family could be seen by Murdock as broken as the father was once present and is know, meaning the parents once had a sexual relationship and a child together, putting them in Murdock’s category as a nuclear family.Kathleen Gough found faults to Murdock’s theory by studying other societies; she studied mainly a South Indian tribe, the Nayar.

The Nayar hade many customs and traditions which would not put them in the category of Murdock’s Nuclear family. They practice polygamy; this is seen as a normal occurrence as it means there is no risk in the population falling.Murdock’s theory would also not apply as he states that the mother and father of the child are to be known, but in the Nayar tribe fathers were not known and it is the brother who takes care of the children’s mother and provides her with financial support. However as this society has disappeared it could be argued that Murdock was right and that not only is the nuclear family universal it is the best family situation.

In Murdock’s view another society, which wouldn’t fit into the nuclear family situation, would be the new world black family, as these types of families from west India often don’t contain any adult male and are mainly revolved around the children and women. Polygyny was also widely spread in this society to ensure there were always children and no decrease in the population. Being mainly a matrifocal society the core unit of the family base is mother and child, it also includes a wide number of aunts, grandmothers and female friends who all help to raise the children, however once again this could be argued to be a broken nuclear family in Murdock’s opinion.This is because the fathers were known in some, not all, situations and the mothers and fathers were once in an relationship, and possibly married, but were separated for a number of reasons, a main one being slavery, the main case was that women and men were split up and the children stayed with there mothers as they were less trouble, and the mothers could still care for them.

The women left in west India were almost always very poor, as they had no man to provide for them, so they had to have a large support group, mainly consisting of female family and friends, creating a generation of ‘independent women’.Another researcher of this was Hannerz, who disagreed with Murdock and said that the nuclear family was no longer the ‘only family’ but the new types of family, such as the new world black family were now ‘accepted and expected’Many other groups would not fit into Murdock’s ‘Nuclear family’ which suggests that he might not be right, another group who would not be in that category is homosexual couples, for the facts that they are not two adults of opposite sex and it is unusual for them to have children of there own, however it is possible in some circumstances such as adoption, or if one of both of the couple has children from a previous relationship, but if one of the partners does have a child from a previous heterosexual relationship it could be seen that there was the basis for a nuclear family and that they could just be part of a broken nuclear family, however this is not the case in most homosexual relationships.There are many other people who see homosexual couples as a variation of the nuclear family, Sidney Callahan suggests that partners in a long-term homosexual relationship would be married if they were legally allowed to therefore making them a family, especially if there are children involved, weeks et al agrees with Callahan and suggests that homosexual relationships with children could be stronger as it is more chosen than a heterosexual relationship.There are also other variations of families which would not come under the ‘Nuclear family’ description, families such as foster families wouldn’t, as the children involvers are neither bio-logical or adopted, this is the same for reconstituted families, as the step parent has no legal relationship to the child/children.

Childless couples would also not fall into the nuclear family category as there are two adults of opposite sex but they do not have children, this is regarded as a bad thing by some sociologists such as Toffler, who talks about the sandwich generation, which is the generation of people in there 50’s and 60’s who have two other generations to take care of, the older generation which needs more medical care as people are living longer, and there children who need more financial support in going to university.Toffler argues that the basic family unit couple, which contradicts Murdock’s, Gough’s and Yanina Sheeran, who argued the basic family core, was the female, ideas.There are also large groups of people who wouldn’t fit into any of these category’s, such as the Kibbutz, where they live in a communities situation rather than a family situation, once again this can however be argued by Murdock’s theory as all of the children know who there parents are and join them regularly for meals. The Mormons are also another example of a alternative family as there is not one couple with many children, a man has many wives as polygamy was popular in some groups of Mormons, so there is no one couple, however all children know who there actually mothers are and the father is obviously known.

There is even many variations of the nuclear family with things such as divorce becoming more common and there is a increasing number of single parent families. Anne Oakley came up with the idea that there is a new variation of the nuclear family, and that Murdock wasn’t necessarily wrong but right for his time. She suggested that, nuclear families are composed of legally married couples choosing voluntarily parenthood, of one or more not too many children.In conclusion the evidence indicates that whether you class a nuclear as universal, it is all dependant on how you define family.

It appears that all societies have a variet of families, it could be argued that all of these come from the original form of a nuclear family, and that all society’s there was no nuclear family have died out. Diana Griffins argued that the relationship was the core to a family, “relationships are universalâ€¦but all forms that these can take are infinitely variable and can be changed and challenged as well as embraced”.

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