Memristor Spice Model For Designing Memristor Circuits Economics Essay

Memristor Spice Model For Designing Memristor Circuits Economics Essay Memristors are novel electronic devices, a device that can be used and give a great advantage in many applications such as memory, logic, neuromorphic systems and so on. A computer model of the memristor would be a useful tool to analysis circuit behavior to help in develops application of this memristor as passive circuit element via simulation. In this paper, we incorporate a memristor SPICE for designing memristor circuit which is more focusing on non-linear model and analog circuits. SPICE model would be appropriate way to describe real device operation. We incorporating the memristor with various window functions that have been proposed in non linear ion drift memristor devices. In investigating and characterizing the physical electronic and behavioral properties of memristor devices, the circuit analysis of the proposed memristor models are then been studied. The simulation output should have a current-voltage hysteresis curve, which looks like bow tie. The loops map the switch ing behavior of the device. Then, we come out with a simple analog circuit which in this case we construct a simple integrator op-amp and differentiator op-amp circuit and make comparison between memristor implemented circuit and normal circuit. The research verifies the proposed memristor model, the possibilities of implementing memristor model and the advantage implementing the memristor in analog circuit. Keywords memristor, SPICE model, non linear, window functions, analog circuit. Introduction Memristor is the contraction of memory resistor which is a passive device that provides a functional relation between charge and flux. It is a two-terminal circuit element in which the flux between the two terminals is a function of the amount of electric charge that has passed through the device [1]. A memristor is said to be charge-controlled if the relation between flux and charge is expressed as a function of electric charge and it is said to be flux-controlled if the relation between flux and charge is expressed as a function of the flux linkage [2]. In 1971, Leon Chua proposed that there should be a fourth fundamental passive circuit element to create a mathematical relationship between electric charge and magnetic flux which he called the memristor which is short for memory resistor [2]. The current is defined as the time derivative of the charge. The voltage is defined as the time derivative of the flux according the faraday law. A resistor is defined by the relationship between voltage and current dv=Rdi, the capacitor is defined by the relationship between charge and voltage dq=Cdv, the inductor is defined by the relationship between flux and current dà Ã¢â‚¬  =Ldi. The fourth fundamental circuit element completes the symmetry of the relation between charge and magnetic flux dà Ã¢â‚¬  =Mdq. Table 1 show the relationship between the fundamental circuit element. Basic two terminal devices Equation Relationship between fundamental circuit element Resistor,R dv=Rdi v and i Capacitor,C dq=Cdv v and q Inductor,L dà Ã¢â‚¬  =Ldi i and à Ã¢â‚¬   Memristor,M dà Ã¢â‚¬  =Mdq q and à Ã¢â‚¬   Table 1: The four fundamental element (resistor, capacitor, inductor and memristor). In 2008, Stanley Williams and his team at Hewlett Packard had succesfully fabricated the first memristor in physical device form which is a long wait from Leon Chua discovery in 1971 [3]. Memristance is a property of memristor. When the charge flows in one direction through a circuit, the resistances of the memristor increase. The resistance decreases when the charge flows in the opposite direction in the circuit. If the applied voltage is turned off, thus stopping the flow of charge and the memristor remembers the last resistance that it had [1]. In HP memristor model, to create a memristor, they used a very thin film of titanium dioxide (TiO2). The thin film is then sandwiched between the two platinum (Pt) contacts. One side of TiO2 is doped with oxygen vacancies denoted as TiO2-x which x is usually 0.05. The oxygen vacancies are positively charged ion and make it conductive, thus it behaves as a semiconductor. Another side of the TiO2 junction is undoped. The undoped region has insulating properties. The device established by HP is shown in Figure 1 [3]. Figure 1: Memristor model adapt from [3]. When a positive voltage is applied, the positively charged oxygen vacancies in the doped TiO2-x layer are repelled and moving them towards to the undoped TiO2 layer. When the boundary between the two materials moves, the percentage of the conducting TiO2-x layer is increase. Thus, the conductivity of the whole device increases. When a negative voltage is applied, the positively charged oxygen vacancies are attracted and pulling them out of TiO2 layer. This increases the amount of insulating TiO2, thus increasing the resistivity of the whole device. When the voltage is turned off, the oxygen vacancies do not move. The boundary between the two titanium dioxide layers is frozen. This is how the memristor remembers the voltage last applied [1]. Methodology Our aim in this research is to provide a simulation program adequately simulates and can be used as a circuit element in design work. To model the electrical characteristics of the memristor, SPICE would be appropriate way to describe real device operation [4]. Moreover, using the model as a sub-circuit can highly guarantee a reasonable high flexibility and scalability features [5]. We use LTSPICE to create a memristor model and design new symbol of the memristor circuit for the simulation because LTSPICE is much easier to handle compared to others. On the other hand, LTSPICE is a freeware and it will give a great advantage to the students in doing research for this newly devices. We use SPICE model that been adapt from [6] and we made some adjustment so we can use it for several window functions that has been proposed for non linear ion drift model. The SPICE model is created based on the mathematical model of the HP Labs memristor. After the memristor has been modeled, we first studied the difference between proposed memristor and then we will start design and implement the memristor with an analog circuit. We also investigate and made a comparison between the memristor circuit with analog circuit to see the difference and study the behavior of the circuits. Model Of The Memristor from HP Labs In the model of a memristor presented here, there is a thin semiconductor film that has two regions, one with a high concentration of dopant that behaves like a low resistance called RON and the other with a low dopant concentration with higher resistance called ROFF [3]. The film is sandwiched between two metal contacts as in figure 1. The total resistance of the memristor, RMEM, is a sum of the resistances of the doped and undoped regions, w is the width of the doped region and D is the total length of the TiO2 layer. ROFF and RON will be the limit values of the memristor resistance for w=0 and w=D. The ratio of the two resistances is usually given as 102 103. (1) (2) From the ohms law relation between the memristor voltages and current, we get (3) Then, we insert (1) into (3). The voltage v(t) across the device will move the boundary between the two regions causing the charged dopants to drift. So, there is a drift ion mobility  µv in the device. The change of the boundary is denoted as in (5). (4) (5) To get x(t), we then integrates the right side of equation (5) which then yields the following formula (6) By inserting equation (6) into equation (4) and since usually RON (7) Where  µv is the average drift velocity and has the units cm2/sV, D is the thickness of titanium-dioxide film ROFF and RON are on-state and off-state resistances and q(t) is the total charge passing through the memristor device. Non Linear Ion Drift Model Even a small voltage across the nanodevices will produce a large electric field [7]. This causing the ion boundary position will move in a decidedly non-linear. Nonlinear dopant drift adds nonlinear window function f(x) to the state equation. The window function decreases as the state variables drift speed approaches the boundaries until it reaches zero when reaching either boundaries [8]. The speeds of the movement of the boundary between the doped and undoped regions are depending on several factors. (8) Where  µv is the dopant mobility. The speed of the boundary between the doped and undoped regions decreases gradually to zero at the film edges [1]. We simulate the nonlinear ion drift memristor model with these window function to see the difference and the issue that been faced by them. Window Function Window function is a function of the state variable. Window function forces the bounds of the device and to add nonlinear behavior close to these bounds. In other words, it creates the boundary for the memristor. Any effective window function should therefore fulfill the following conditions [8]: Take into account the boundary conditions at the top and bottom electrodes of the device; Be capable of imposing nonlinear drift over the entire active core of the device; Provide linkage between the linear and nonlinear dopant drift models; Be scalable, meaning a range of fmax(x) can be obtained such that 0 à ¢Ã¢â‚¬ °Ã‚ ¤ fmax(x) à ¢Ã¢â‚¬ °Ã‚ ¤ 1; Utilize a built-in control parameter for adjusting the model. There are several window functions that have been proposed for non-linear model till date which are by Strukov, Joglekar and, Biolek, and Prodromakis. Strukov proposed the following window function [3]. (9) However, as we can see in the figure 2, this window function lacks of flexibility. Figure 2: Plot of Strukov window function. Another window function was proposed by Joglekar [4], which has a control parameter p which is a positive integer. The purpose of having a control parameter as an exponent is to incorporate scalability and flexibility in window function f(x) that describes the dopant kinetics. (10) Figure 3 displays a graphical representation of the window function described by Joglekar for various p parameter (p=1, 5 and 10). This control parameter controls the linearity of the model, where it becomes more linear as p increases. This window function ensures zero drift at the boundaries. From the plotted graph, we noticed that the maximum f(x) value is occurs at the center of the device and zero is obtained at two boundaries. However, a significant liability of this model lies in the fact that if w hits any of the boundaries (w = 0 or w = D) the state of the device cannot be further adjusted. This will be from now on termed as the terminal state problem. Figure 3: Plot of Joglekar window function for p=1, 5 and 10. Then, Biolek proposed another window function that allows the memristor to come back from the terminal state problem. (11) The reversed bias is now should move back the state variable after it reaches either boundary. This feature is described by a current dependent step function, stp(i), which is a part of a new window function f(x) that behaves differently in each voltage bias direction. (12) Figure 4: Plot of Biolek window function for p=1, 5 and 10. Figure 4 displays a graphical representation of the window function described by Biolek for various p parameter (p=1, 5 and 10). When x starts at 0, we noticed that the function equal to 1. As x increase approaching D, the function approaches 0. Once the current reverse the direction, the function immediately switch to 1. As x decrease back to 0, the function also decreases to 0. Biolek window function eliminates convergence issues at the devices boundaries. The last window function for non-linear model is proposed by Prodromakis [8]. (13) Figure 5 displays a graphical representation of the window function described by Prodromakis for various p parameter (p=1, 5 and 10). As we can see, it allows the window function to scale upwards which implies that fmax(x) can take any value within 0 Figure 5: Plot of Prodromakis window function for p=1, 5 and 10. SPICE Model of Memristor Figure 6: Stucture of the SPICE model from [6]. In the above circuit in figure 6, VMEM is the input voltage and Imem is modeled to be the current through the memristor. The flux is calculated by integrating the voltage VMEM and the charge is calculated by integrating the current IMEM. Figure 7: Resistive port of the memristor model. As we can see in figure 7, the circuit is actually referred to total resistor RMEM. RMEM (x) = ROFF -xà ¢Ã‹â€ Ã¢â‚¬  R where à ¢Ã‹â€ Ã¢â‚¬  R= ROFF-RON. ROFF is the resistor in series voltage source whose terminal voltage is controlled by the formula -xà ¢Ã‹â€ Ã¢â‚¬  R. Figure 8: Differential equation modeling of the memristor. Figure 8 shows the differential equation modeling of the memrsitor. It consist a part of the voltage controlled source xà ¢Ã‹â€ Ã¢â‚¬  R and the differential equation from equation (6) which serves as an integrator of the quantities on the right side of the state equation (6) which is to get the value of normalize x. EMEM is the voltage source whose terminal voltage is controlled according to the formula -xà ¢Ã‹â€ Ã¢â‚¬  R. GX is a current source whose current is controlled according to the equation IMEMf(V(x)) where V(x) is the voltage across the capacitor Cx and it models the normalized width x of the doped layer. F(V(x)) is the window function, k is  µvRON/D2 and x0 is the initial voltage of the capacitor.[6]. The relation between memristor current and voltage is modeled as on the basis of RMEM (x) = ROFF -xà ¢Ã‹â€ Ã¢â‚¬  R where à ¢Ã‹â€ Ã¢â‚¬  R= ROFF-RON. The voltage V(x) across the capacitor CX models the normalized width x of the doped layer. The initial state of x is modeled by the initial voltage of the capacitor. The flux is calculated by the time-integral of voltage, and the charge is calculated by the time-integral of current. Result and Discussion All models were simulated in LTSpice using SPICE model that was given in [6], we add new nonlinear window functions that was proposed by prodromakis and strukov to the model and compare all suggested window functions. memristor Figure 9: Memristor circuit. Figure 9 shows configuration of single memristor for measuring the behavior of memristor model in LTSPICE with a sine wave input voltage of 1.2V with 1Hz frequency. The values for the memristor parameters  µv, D, RON, ROFF and RINITIAL are 10-10cm2s-1V-1, 10 nm, 100ohm, 16kohm and 11Kohm. All model are using same window function parameter p=10. C:UsersFadzDesktopresultstrukovstrukov1.png Figure 10: Strukov memristor model voltage, IMEM, RMEM and normalized x. Figure 10 shows the simulation result of memristor SPICE model for Strukov window function of voltage, IMEM, RMEM and normalized x. As we can see, the current of the memristor, IMEM is varying up to approximately 100 µA for maximum of 1.2V voltage applied. The RMEM for this model show that the values are in range of 11kOhm till 12kohm which means the effect of the voltage applied to the memristor only give slightly changes on the value of the memristor. Noticed that when positive voltage is applied, the conductivity of the device increases thus the memristance is decrease. When negative voltage is applied, the resistivity of the device increase thus the memristance is also increase. This verifies the memristive system on the device. In normalize x graph, we also noticed that the normalized x is at higher state in the beginning. Figure 11 shows the I-V characteristic of the devices and the relationship between charge and flux. The charge and flux curve curves confirms the well known fact that there is a one-to-one correspondence between them in spite of the 1-4 hysteresis effect. Strukov memristor shows lack of flexibility of controlling the device. C:UsersFadzDesktopresultstrukovstrukov4.png Figure 11: Strukov memristor model I-V loop hysteresis and relationship of charge and flux. C:UsersFadzDesktopresultjoglekarjoglekar1.png Figure 12: Joglekar memristor model voltage, IMEM, RMEM and normalized x. Joglekar window function seems to be promising as the existence of controlling parameter. Figure 12 shows the simulation result of memristor SPICE model for Joglekar window function of voltage, IMEM, RMEM and normalized x. Same as strukov memristor, when positive voltage is applied, the conductivity of the device increases thus the memristance is decrease. When negative voltage is applied, the resistivity of the device increase thus the memristance is also increase. The current of the memristor, IMEM is varying up to approximately 300 µA for maximum of 1.2V voltage applied. Joglekar window function give higher current compared to others. It shows that the current in the memristor are much easier to move. The RMEM are within range of nearly 0ohm to 11kohm which give full range of value for the memristor. Figure 13 show the I-V hysteresis loop of the devices and the relationship between charge and flux. The switching behavior is much more sensitive on the voltage level than Strukov w indow function. But, in term of stability, Joglekar window function cannot perform for an arbitrary length of time. This failure is caused by the convergence issue where when the memristor reach w=0 or w=D, the state of the device cannot be further adjusted. C:UsersFadzDesktopresultjoglekarjoglekar4.png Figure 13: Joglekar memristor model I-V loop hysteresis and relationship of charge and flux. Biolek window functions are supposed to solve terminal state problem as in literature [4]. It should solve the boundry problem of the terminal state. Figure 14 and 15 shows the simulation result of memristor SPICE model for Biolek window function. The current of the memristor, IMEM is varying up to approximately 220 µA for maximum of 1.2V voltage applied. The RMEM are within range of nearly 1kohm to 11kohm. Figure 15 show the I-V hysteresis loop of the devices and the relationship between charge and flux. From the figures, we observe that the biolek memristor preserve the highly non-linear device characteristic behavior. In addition, Bioleks model allows for general asymmetric I-V device behavior modeling. C:UsersFadzDesktopresultbiolekbiolek1.png Figure 14: Biolek memristor model voltage, IMEM, RMEM and normalized x. C:UsersFadzDesktopresultbiolekbiolek4.png Figure 15: Biolek memristor model I-V loop hysteresis and relationship of charge and flux. Prodromakis window functions are also said to solve the boundry issue. Figure 16 shows the simulation result of memristor SPICE model for Joglekar window function of voltage, IMEM, RMEM and normalized x. The current of the memristor, IMEM is varying up to approximately nearly 180 µA for maximum of 1.2V voltage applied. The RMEM are within range of nearly 3kohm to 11kohm. C:UsersFadzDesktopresultprodromakisprodromakis1.png Figure 16: Prodromakis memristor model voltage, IMEM, RMEM and normalized x. Figure 17 show the I-V hysteresis loop of the devices and the relationship between charge and flux. The hysteresis loop is shown to be asymmetrical while the OFF state of the device is highly non-linear compared with other. C:UsersFadzDesktopresultprodromakisprodromakis4.png Figure 17: Prodromakis memristor model I-V loop hysteresis and relationship of charge and flux. In comparing of I-V characteristic hysteresis loop, as we can see in figure 18, it shows all hysteresis loops for all proposed window functions. By using same parameter we can see the difference in each model. Joglekar window function seems to have a strong memristance compared to others.All models seem to be a good approximation of the measurement of the real memristor produces by HP Labs. But, Prodromakis memristor model satisfies all the prerequisites and improves on the shortcomings of existing models. C:UsersFadzDesktopresultall iv loop hysteresisiv hysteresis loop all.png Figure 18: I-V Hysteresis Loop for all models. C:UsersFadzDesktopresultdiff parameterprodromakis p=1, p=5, p=10.png Figure 19: Prodromakis I-V Hysteresis Loop when p=1, p=5 and p=10. Then, we try change the parameter of p of the model. In this case, we use prodromakis memristor model and change the value of integer p=1, p=5 and p=10 to see the difference. As we can see in figure 19, as the value of p is increase, the hysteresis is shrinking. Similar with changing the parameter p, figure 20 also confirm that the hysteresis shrinks at higher frequencies. C:UsersFadzDesktopresultdiff frequency1hz-5hz.png Figure 20: Prodromakis I-V Hysteresis Loop when frequency f=1Hz, f=2Hz and f=5Hz. In term of power dissipation, as we simulates our results. We can get the value of maximum IMEM for each model. We can calculate the power by using P=IV equation. Table 2 show the maximum power dissipation for each memristor. Memristor model Max IMEM,  µA Power, W Strukov 100 µA 120 µW Joglekar 300  µA 360 µW Biolek 220 µA 264 µW Prodromakis 180  µA 216 µW Table 2: IMEM and Power dissipation for all at the memristor. As in table 2, we can see that the Strukov model give lowest power which is 120 µW while Joglekar model give much higher power dissipation which is about 360 µW compared to the others. We also noticed that as the memristor model is improves, the power become lesser. Prodromakis give quite good power dissipation which is 216 µW as the best windows function and model as till now. In implementing memristor with analog circtuit, we pick a two simple analog circuit to be tested. Figure 21 shows the SPICE topology of the memristor based integrator op amplifier with the input voltage Vp-p=2.4V from -1.2V to 1.2V and C1=25 µF. Using the memristor model that we create earlier with various types of window functions, we see the difference on the simulated result on each model. The values for the memristor parameters are same for all model with uv, D, RON, ROFF and RINITIAL are 10-10cm2s-1V-1, 10nm, 100ohm, 16kohm and 11Kohm. memristor integrator op amp Figure 21: Memristor Implemented Integrator Circuit C:UsersFadzDesktopresultintegrator+ve integrator .png Figure 22: Positive Integrator simulation C:UsersFadzDesktopresultintegrator-ve integrator .png Figure 23: Negative Integrator simulation Figure 22 and 23 shows the simulation result for the implemented memristor integrator op amplifier for positive input and negative input respectively. In this case, we implement prodromakis memristor to the integrator circuit. As we know, the integrator acts like a storage element that produces a  voltage  output which is proportional to the integral of its input voltage with respect to time. The magnitude of the output signal is determined by the length of time a voltage is present at its input as the  current  through the  feedback loop  charges or discharges the  capacitor  as the required  negative feedback  occurs through the capacitor. For positive starting input, we vary the voltage from 1.2V down to -1.2V and going back to 1.2V over time. When positive voltage are applied in the beginning, the output voltage tend to discharge and drop from 0V to negative voltage and charging back to 0V when the input voltage are drop to negative voltage. The output for neg ative voltage applied from starting point give a vice versa result. The charging and discharge are depends the voltage applied over time and the value of the capacitor. We can say the memristor models give quite good result for an integrator. Figure 24: Memristor Implemented Differentiator Circuit. C:UsersFadzDesktopresultdifferentiatordifferentiator.png Figure 25: Saw tooth input of Memristor implemented differentiator op-amp simulation. Figure 25 shows the simulation result for the implemented memristor differentiator op amplifier. We are using prodromakis memristor model for the memristor implementation. As we know, for differentiator op-amp, the magnitude of its output is determined by the rate at which the voltage is applied to its input changes. The faster the input voltage changes, the greater the output voltage becomes. If a saw tooth input signal is applied to the input of the differentiator op-amp a square wave signal will be produced. As we can see in figure 25, the simulation shows a quite good result for differentiator. We also noticed some spikes at the output voltage. Each spikes occurs only occurs the brief moment the saw tooth is changing from one level to the next. The voltage spikes represent a temporary output voltage. Conclusion As a conclusion to this research is that it could bring a new light of familiarization in the integration of memristive components in any kinds of electronic devices that are at nanoscale. It is useful to have a computer model of the memristor as a tool for the analysis of the behavior of the circuits in developing application of this memristor as passive circuit element via simulation. SPICE model will definitely help us to conduct interesting simulation experiments and can be of great importance for such a research in future while the memristor are still hard to fabricate to study the behavior of the circuit. Different models with strong behavior and reason give a lot of benefits in development purpose to create the possibilities of the implementation in an integrated circuit. The possibilities for implementation of the memristor with analog circuit are wide open. Appendix .SUBCKT memristor plus minus PARAMS: + Ron=100 Roff=16K Rinit=11K D=10N uv=10F p=10 *********************************************** * DIFFERENTIAL EQUATION MODELING * *********************************************** Gx 0 x value={ I(Emem)*uv*Ron/D**2*f(V(x),p)} Cx x 0 1 IC={(Roff-Rinit)/(Roff-Ron)} Raux x 0 1T * RESISTIVE PORT OF THE MEMRISTOR * *********************************************** Emem plus aux value={-I(Emem)*V(x)*(Roff-Ron)} Roff aux minus {Roff} *********************************************** *Flux computation* *********************************************** Eflux flux 0 value={SDT(V(plus,minus))} *********************************************** *Charge computation* *********************************************** Echarge charge 0 value={SDT(I(Emem))} *********************************************** * WINDOW FUNCTIONS * FOR NONLINEAR DRIFT MODELING * *********************************************** *proposed by joglekar ;.func f(x,p)={1-(2*x-1)**(2*p)} *proposed by biolek ;.func f(x,i)={1-(x-stp(-i))**(2*p)} *proposed by prodromakis ;.func f(x,p)={1-(((x-0.5)**2)+0.75)**p} *proposed by strukov .func f(x,p)={x-x*2} .ENDS memristor Acknowledgment This paper participates in the IEEE Student Conference Research Development SCORED 2012. The author would like to thank Dr. Wan Fazlida Hanim bte Abdullah for being supervisor in this final year project. The author also would like to thank Universiti Teknologi MARA for funding the research work through the Excellence Fund Grant 600-RMI/ST/DANA 5/3/RIF(360/2012).

The Fear Of Science :: essays research papers

The Fear of Science To live in the today's world is to be surrounded by the products of science. For it is science that gave our society color television, the bottle of aspirin, and the polyester shirt. Thus, science has greatly enhanced our society; yet, our society are still afraid of the effect of science. This fear of science can be traced back to the nineteenth century where scientist had to be secretative in experimenting with science. Although science did wonders in the nineteenth century, many people feared science and its effects because of the uncertainty results of science. Our thrist for science can be traced back through many decades. However, the nineteenth century society felt that science was a great investment towards a better life. This investment in science gave the nineteenth century society the discovery of light waves and radio waves, the electric motors, the first photograph and telephone, and the first publication of the periodic table. Science also caused an uproar in society when Charles Darwin published The Origin of Species, which became the scientific basis for the study of the evolution of humans. Many people in the nineteenth century detested Darwin's theory of the evolution of man because it went against their religion, which believed that God created the world. Science, soon, developed the big bang theory, which states that earth was created by the attraction of atoms. The nineteenth century society was afraid of science because it contradicted their beliefs, and was afraid that the results of science would lead to the destruction of mankind. Thus, the study of science was limited because of fear of its effects. The fear of the effects of science was expressed in literature. Novels like Dr. Jekyll and Mr. Hyde, the Time Machine, and Frankenstein showed the dangers of science and that science would soon lead to the destruction of mankind. The novel Frankenstein is about a man name Victor Frankenstein who wanted to tamper with life and death by "exploring unknown powers, and unfold to the world the deepest mysteries of creation." (Frankenstein, pg.40) He acquired the knowledge of science when he attended the university of Ingolstadt, and once the knowledge of science was gained, Frankenstein went to his secret laboratory to create a creature with gigantic stature. At first, Frankenstein had doubts about creating a human being; however, with "the improvement which every day takes place in science and mechanics, [he] was encouraged to hope [his] present attempts would at least lay the foundation of future success." (Frankenstein, pg.47) Once Frankenstein created his human being, his dream was vanished because he had accomplished his dream.

History of christmas :: essays research papers

History of the Celebration of Christmas People have celebrated a mid-winter festival since pre-historic times. They marked the beginning of longer hours of daylight with fires and ritual offerings. The Roman festival of Saturnalia -- a time for feasting and gambling -- lasted for weeks in December. Germanic tribes of Northern Europe also celebrated mid-winter with feasting, drinking and religious rituals. It's thought that Jesus of Nazareth was born in springtime. A Pope, Julius I, chose December 25th for the celebration of his birth in the 4th century -- to include a Christian element in the long-established mid-winter festivals. Also in the 4th century, a bishop in Turkey who came to be called St. Nicholas was known for good deeds involving children. St. Nicholas is illustrated in medieval and renaissance paintings as a tall, dignified and severe man. His feast day on December 6 was celebrated throughout Europe until about the 16th century. Afterwards, he continued to be known in Protestant Holland. Dutch children would put shoes by the fireplace for St. Nicholas or "Sinter Klaas" and leave food out for his horse. He'd gallop on his horse between the rooftops and drop candy down the chimneys into the children's shoes. Meanwhile, his assistant, Black Peter, was the one who popped down the chimneys to leave gifts behind. Dutch settlers brought the legend of Sinter Klaas to North America -- where we came to know him as Santa Claus. Clement Clarke Moore first described the â€Å"jolly old elf† with his sleigh drawn by reindeer, in the poem "The Night Before Christmas. Although it was never celebrated in biblical times, Christmas is celebrated in local churches here in Visalia, California in praise of the fact that God loved us so much; he sent his one and only son to earth. He was wholey god and wholey man. Whereas we have succumbed to the temptations of this earth, Jesus was able to overcome all temptations and live a sinless life. He was then crucified as the perfect sacrifice for our sins. One cannot understand why we celebrate the birth of Christ without seeing the other end of his life. He was crucified for our sins and resurrected. Christmas was declared a Federal Holiday in America on June 26, 1870 under the government headed by President Ulysses S.

Theme of Isolation in Gilman’s The Yellow Wallpaper, Steinbeck’s The Ch

Despite differing story lines, Charlotte Gilman’s The Yellow Wallpaper, John Steinbeck’s The Chrysanthemums and Kate Chopin’s The Awakening, depict the same suffering; the isolation that women have been forced to endure throughout history. In the time period that all three characters were placed, it was culturally acceptable for wives to be dominated by their husbands; their responsibility revolving around the needs of their children and those of their spouse. Most women simply did not have a means or an idea of how to rebel against their husbands. The women in all three stories are protagonists who have poor relationships of emotional attachment with their spouses. While the main character of Gilman’s story endures multiple psychotic breaks, Elisa Allen of Steinbeck’s piece is quite the opposite: a very strong and powerful woman. Gilman’s character finally resolves her problems by breaking free, where Elisa remains frustrated with her ignora nt husband and Edna of ultimately escapes through death. This dominance, this isolation, is a cycle maintained by society and the men within it. A cycle that these three short stories prove to be nothing more than destructive and harmful for families as a whole. Following these storylines, there are three key points to address: the relationship between husband and wife, women’s standings within society and finally, the end that it drives these originally normal women to. At first Gilman’s character tries to rebel against her husband through writing, (something she has been forbidden from doing while on her hiatus). In â€Å"The Yellow Wallpaper,† Gilman implies that although her husband is â€Å"very careful and loving† (Gilman 449) she is also her condemner. Gilman addresses the fact that John prev... ...tanding of equality; but in these novella’s the reader can only see the loneliness, inner-turmoil, and feelings of inadequacy that plagued every one. The reader learns that forcing a person, particularly a woman, into such a place of exaggerated separation can have grave consequences. Works Cited Chopin, Kate. "The Awakening." The Norton Anthology of Literature by Women: The Traditions in English. 2nd ed. Comp. Sandra M. Gilbert and Susan Gubar. New York: Norton, 1996. 1011-101. Print. Gilman, Charlotte Perkins. â€Å"The Yellow Wallpaper.† Literature for Composition: Reading and Writing Arguments about Essays, Fiction, Poetry, and Drama. Ed. Sylvan Barnet, William Burto, and William E. Cain. 8th ed. New York: Pearson Longman, 2007. 765-75. Print. Steinbeck, John. "The Chrysanthemums." The Seagull Reader Stories. New York: W.W. Norton & Company, Inc., 2008.

Human Element Essay

This study is related to an important topic that influence the evolution of both public and private institutions via improving human resource management and, hence improving the human resource itself, which occupies a vital and outstanding position in the comprehensive development strategies. Also, because of the role that effective human resource plays in planning and implementing development. Therefore, human element is considered an investment in the bright future of the institutions. Human resource is an innovative element that is described as an interactive rather than a rigid element, which is able to coordinate, maintain a balance between the various constituent of production and take the responsibility for the results of operations. On the other hand, external circumstances, such as the economic, political, social cultural and environmental factors, affect human element more than any other element. The researcher has selected Giad Automobiles Manufacturing Co. LTD, as a case study to introduce the influence of human resource development on employees’ performance. The results have been determined based on the analysis of the employees’ responses to the questionnaire that surveyed the employees’ community in the company. The questionnaire has tested the following hypotheses: 1- There is a relationship between the development of human resource management and the development of the working human element. 2- There is a relationship between the development of the human element and the development and improvement of performance in the institution, which leads to an increase in the production and, hence achieving the objectives. The researcher has applied several methodologies, such as case study methodology, descriptive methodology, and statistical analysis. The researcher has confirmed the validity of all the above hypotheses, in addition to the research outcomes that have led the researcher to conclude the study with some suggestions and recommendations.

Organizational Culture of Virgin Group Essay

1. Describe the culture of Virgin group by seven dimension of organization culture. Organizational culture has been described as the shared values, principles, traditions, and ways of doing things that influence the way organizational members act. Actually, it can divided seven dimension of organizational culture which are attention to detail, outcome orientation, people orientation, team orientation, aggressiveness, stability and innovation and risk taking, and now I will use these seven dimensions to describe the culture of virgin. The first dimension used in this culture of virgin is attention to detail. It is the degree to which employees are expected to exhibit precision, analysis, and attention to detail. It is such a culture gives a competitive advantage to companies by helping them differentiate themselves from others. Like this article, the virgin airline has a lot of competitors like 747airline. They provide heterogeneous products and the virgin airline put their selling point to their services that their crews are smiling, cheerful and pleased to help, let the passengers wanting to fly with them again. Also, the virgin America sweeps the travel awards for service and quality. Although their planes are new, with great interiors and entertainment, the great service of its crews is what wins so many plaudits. Furthermore, they employ a general manager in the Caribbean. He tried to change the way things were done, discouraged the staff from drinking their guests that reducing the staff morale. As he didn’t get the degree on attention to detail, then he was being replacement. The second dimension in this culture is people orientation. It is the degree to which management decisions take into account the effects on people in the organization. It emphases on individual rights and expectation of treating people with respect and dignity. In this article, when the author was running Virgin Records, a member of the talent-scouting team was stealing and selling boxes of records to local secondhand shops. But he didn’t fire the staff and just gave him a severe warning and a second chance. He expected the staff to learn from his mistake and get back to doing his job. As the experience of the author that he fell foul of the customs and excise people as trying to bring records into the UK. He was given a fine, a second chance and have tried to make the most of it ever since. This has made him much more accepting and forgiving of people’s mistakes. Also, the virgin airline treats their staff as family units and makes them feel that their company is their second home. They will hold parties in the weekend, make sure all the staff can participate the parties and help them build the relationship between staff and manager. That is how the virgin airline treating their staff. The third dimension in this culture is team orientation. It is a degree to which work is organized around teams rather than individuals. It is collaborative and emphases on cooperation among employees. In this article, the writer mentioned about how to be a good leader to lead people well. He said that a good leader must know the team, its strengths and weakness; socializing and listen to the team is the key of being a good leader. A good leader can led their teammate well, can motivate the staff morale and build the relationship between the team. He also said that a bad leader can destroy a business very quickly. As they employed a general manager in Caribbean who tried to change the way things were done. The manager discouraged the staff from drinking with guests that decreased the staff morale and broke the trust of management. So they replace the manager and restore the staff morale and the sense of management’s trust which had been broken. The fourth dimension in this culture is innovation and risk taking. It is the degree to which employees are encouraged to be innovative and take risk. Through this article, Brett Godfrey showed his business plan to the author, which outlining the start-up of a low-cost carrier in Australia to take on Qantas and Ansett in their domestic market. He has expanded Blue and its sister airline to the United States, New Zealand, Thailand and South Africa. The company give them brand support and the space to go build the new business themselves like Virgin Active. Also, Matthew Bucknall and Frank Reed had bought out some innovative idea like the idea of a family-friendly health and fitness club in 1999. These planning and ideas are innovative, but at the same time they need to take the risk on running the ideas and planning. In this article, we can find out four dimension of organizational culture. A top company must have strong organizational culture that employees are more loyal than weak organizational culture, creates a stronger employee commitment to the organization, and the strong organizational culture is associated with high organizational performance. Also, if the value of the culture is clear and widely accepted, employees can know what they are supposed to do and what expected to them, so they can act quickly to take care of problem. 2. How culture affect the manager? A culture usually reflects the vision of organization founder. They will articulate the vision of what they want the organization to be. The small size of most new organizations makes it easier to instill the vision with all organizational members. Also, organizational practices are also one of the impacts on culture. They can find out the information about the organization and determine the most suitable for organization through practices. The top management behavior has a major impact on culture too, that the action of top management can lead to undesirable outcomes. Organizational culture can divide into four types. They are open systems, human relation, internal process and rational goal. A culture will predominately affect the manger in four ways, which are controlling, leading, organizing and planning. In the leading of the management, the mangers are able to use democratic leadership style that allows employees participate in decision-making progress, but not only individuals in the open systems and human relation culture. Through these two types of culture, the mangers require visionary leadership, responsive behavior and also tend to be participative, considerate and supportive. Also, the mangers in rational goal culture are also able to use democratic leadership style and tend to be directive, goal oriented and functional. On the other hand, the mangers in the internal process culture will be more likely to use autocratic leadership style that they are tend to be conservative and caution. In the planning of the management, they will more likely to take the risk of the plan in open systems culture in the large extent, which this culture is emphasis on creativity and innovation that the employee will have some innovative idea when planning. In rational goal and human relation culture, the manger will take risk on planning in the small extent. But in the internal process culture, the manger are not willing to take the risk on planning, which their company are conservative and cautious. In the human relation and open system culture, they will likely develop the plan by team, but the mangers will likely develop the plan by individual in the rest of the cultures. In the controlling of managers, the control system will be more flexible in human relation and open systems culture, which likely allow employees to control their own action. But in the rest of the cultures, the control system will be inflexible that the managers need their employees follow their rules and procedures. In the open system culture, the manager may able to take the risk to produce the product if exceeding the budget. On the other hand, the manager in internal process culture will prefer cutting the cost or will not produce the product rather than taking the risk to release the product into the market. In the organizing of the mangers, their employees can have more autonomy in their jobs in the human relation and open system culture, but less autonomy of employees in the rest of the cultures. Through the rational goal and internal process culture, they will be able done their task by individual rather than team. On the other hand, in human relation and open system, they will prefer to finish the task by team compare to individual and their manager will be likely being decentralization, that increase the decision-making authority of employees, but the rest of culture not. A culture will affect the mangers what they can or cannot do and how they manage. A good manger should know the culture of their companies deeply, that can help them to know what to do and not do and identify their role on managing a team or company.

Transitions in lifespan Development

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