vnu ept speaking topics part 3 6 10

Generalized Variational Principle for Dissipative Hydrodynamics: Shear Viscosity from Angular Momentum Relaxation in the Hydrodynamical Description of Continuum Mechanics 45 fluids, including the simplest of them, is described by the Navier-Stokes equation, then the only available value, which could relax in all cases, and hence could be considered as common scalar internal parameter, is the mean distance between molecules in gas or liquid. In the condensed and especially in the solid media the mutual space placement of atoms becomes to be essential, hence a space variation of their mutual positions, holding rotational invariance of a body as whole, has to be described by symmetrical tensor of the second order. Hence the corresponding internal parameter could be the same tensor. Thus, the discrete structure of medium on the kinetic level predetermines existence, at least, of mentioned internal parameters, responsible for relaxation. 3.2 Shear viscosity as a consequence of the angular momentum relaxation for the hydrodynamical description of continuum mechanics As shown in the previous section, it is possible to derive the system of hydrodynamical equations on the GVP basis for viscous, compressible fluid in the form of Navier-Stokes equations. However for the account of terms responsible for viscosity it is required to introduce some tensor internal parameter ik ξ in agreement with Mandelshtam-Leontovich approach (Mandelshtam & Leontovich, 1937). Relaxation of this internal parameter provides appearance of viscous terms in the Navier-Stokes equation. It is worth mentioning that the developed approach allowed to generalize the Navier-Stokes equation with constant viscosity coefficient to more general case accounting for viscosity relaxation in analogy to the Maxwell’s model (Landau & Lifshitz, 1972). However the physical interpretation of the tensor internal parameter, which should be enough universal due to general character of the Navier-Stokes equation, requires more clear understanding. On the intuition level it is clear that corresponding internal parameter should be related with neighbor order in atoms and molecules placement and their relaxation. In the present section such physical interpretation is represented. As was mentioned in Introduction the system of hydrodynamical equations in the form of Navier-Stokes is usually derived on the basis of conservation laws of mass M , momentum P  and energy E . The correctness of equations of the traditional hydrodynamics is confirmed by the large number of experiments where it is adequate. However the conservation law of angular momentum M  is absent among the mentioned balance laws laying in the basis of traditional hydrodynamics. In this connection it is interesting to understand the role of conservation law of angular momentum M  in hydrodynamical description. It is worth mentioning that equation for angular momentum appeared in hydrodynamics early (Sorokin, 1943; Shliomis, 1966) and arises and develops in the momentum elasticity theory. The Cosserat continuum is an example of such description (Kunin, 1975; Novatsky, 1975; Erofeev, 1998). However some internal microstructure of medium is required for application of such approach. In the hydrodynamical description as a partial case of continuum mechanics the definition of material point is introduced as sifficiently large ensemble of structural elements of medium (atoms and molecules) that on one hand one has to describe properties of this ensemble in statistical way and on the other one has to consider the size of material point as small in comparison with specific scales of the problem. A material point itself as closed ensemble of particles possesses the following integrals of motion: mass, momentum, energy and angular momentum. The basic independent variables, in terms of which the hydrodynamical description should be constructed, are the VIETNAM NATIONAL UNIVERSITY – HO CHI MINH CITY ENGLISH TESTING CENTER VNU – ENGLISH PROFICIENCY TEST SPEAKING – PART OPEN TOPICS Topic “Life is not fair Get used to it.” – Bill Gates Do you agree or disagree with this statement? Give reasons and examples from your reading, experience or observations to support your point of view Topic “Never spend your money before you have earned it.” – Thomas Jefferson Do you agree or disagree with this statement? Give reasons and examples from your reading, experience or observations to support your point of view Topic “Education is not filling a bucket, but lighting a fire.” – William Yeats Do you agree or disagree with this statement? Give reasons and examples from your reading, experience or observations to support your point of view Topic “Without music, life would a mistake.” – Friedrich Nietzs Do you agree or disagree with this statement? Give reasons and examples from your reading, experience or observations to support your point of view Topic 10 “Great minds have purposes, little minds have wishes.” – Washington Irving Do you agree or disagree with this statement? Give reasons and examples from your reading, experience or observations to support your point of view Generalized Variational Principle for Dissipative Hydrodynamics: Shear Viscosity from Angular Momentum Relaxation in the Hydrodynamical Description of Continuum Mechanics 45 fluids, including the simplest of them, is described by the Navier-Stokes equation, then the only available value, which could relax in all cases, and hence could be considered as common scalar internal parameter, is the mean distance between molecules in gas or liquid. In the condensed and especially in the solid media the mutual space placement of atoms becomes to be essential, hence a space variation of their mutual positions, holding rotational invariance of a body as whole, has to be described by symmetrical tensor of the second order. Hence the corresponding internal parameter could be the same tensor. Thus, the discrete structure of medium on the kinetic level predetermines existence, at least, of mentioned internal parameters, responsible for relaxation. 3.2 Shear viscosity as a consequence of the angular momentum relaxation for the hydrodynamical description of continuum mechanics As shown in the previous section, it is possible to derive the system of hydrodynamical equations on the GVP basis for viscous, compressible fluid in the form of Navier-Stokes equations. However for the account of terms responsible for viscosity it is required to introduce some tensor internal parameter ik ξ in agreement with Mandelshtam-Leontovich approach (Mandelshtam & Leontovich, 1937). Relaxation of this internal parameter provides appearance of viscous terms in the Navier-Stokes equation. It is worth mentioning that the developed approach allowed to generalize the Navier-Stokes equation with constant viscosity coefficient to more general case accounting for viscosity relaxation in analogy to the Maxwell’s model (Landau & Lifshitz, 1972). However the physical interpretation of the tensor internal parameter, which should be enough universal due to general character of the Navier-Stokes equation, requires more clear understanding. On the intuition level it is clear that corresponding internal parameter should be related with neighbor order in atoms and molecules placement and their relaxation. In the present section such physical interpretation is represented. As was mentioned in Introduction the system of hydrodynamical equations in the form of Navier-Stokes is usually derived on the basis of conservation laws of mass M , momentum P  and energy E . The correctness of equations of the traditional hydrodynamics is confirmed by the large number of experiments where it is adequate. However the conservation law of angular momentum M  is absent among the mentioned balance laws laying in the basis of traditional hydrodynamics. In this connection it is interesting to understand the role of conservation law of angular momentum M  in hydrodynamical description. It is worth mentioning that equation for angular momentum appeared in hydrodynamics early (Sorokin, 1943; Shliomis, 1966) and arises and develops in the momentum elasticity theory. The Cosserat continuum is an example of such description (Kunin, 1975; Novatsky, 1975; Erofeev, 1998). However some internal microstructure of medium is required for application of such approach. In the hydrodynamical description as a partial case of continuum mechanics the definition of material point is introduced as sifficiently large ensemble of structural elements of medium (atoms and molecules) that on one hand one has to describe properties of this ensemble in statistical way and on the other one has to consider the size of material point as small in comparison with specific scales of the problem. A material point itself as closed ensemble of particles possesses the following integrals of motion: mass, momentum, energy and angular momentum. The basic independent variables, in terms of which the hydrodynamical description should be constructed, are the 11.1 Switch-Modeling Elements Verilog provides various constructs to model switch-level circuits. Digital circuits at MOS-transistor level are described using these elements. [1] [1] Array of instances can be defined for switches. Array of instances is described in Section 5.1.3 , Array of Instances. 11.1.1 MOS Switches Two types of MOS switches can be defined with the keywords nmos and pmos. //MOS switch keywords nmos pmos Keyword nmos is used to model NMOS transistors; keyword pmos is used to model PMOS transistors. The symbols for nmos and pmos switches are shown in Figure 11-1 . Figure 11-1. NMOS and PMOS Switches In Verilog, nmos and pmos switches are instantiated as shown in Example 11-1 . Example 11-1 Instantiation of NMOS and PMOS Switches nmos n1(out, data, control); //instantiate a nmos switch p mos p1(out, data, control); //instantiate a pmos switch Since switches are Verilog primitives, like logic gates, the name of the instance is optional. Therefore, it is acceptable to instantiate a switch without assigning an instance name. nmos (out, data, control); //instantiate an nmos switch; no instance name p mos (out, data, control); //instantiate a pmos switch; no instance name The value of the out signal is determined from the values of data and control signals. Logic tables for out are shown in Table 11-1 . Some combinations of data and control signals cause the gates to output to either a 1 or 0, or to an z value without a preference for either value. The symbol L stands for 0 or z; H stands for 1 or z. Table 11-1. Logic Tables for NMOS and PMOS Thus, the nmos switch conducts when its control signal is 1. If the control signal is 0, the output assumes a high impedance value. Similarly, a pmos switch conducts if the control signal is 0. 11.1.2 CMOS Switches CMOS switches are declared with the keyword cmos. A cmos device can be modeled with a nmos and a pmos device. The symbol for a cmos switch is shown in Figure 11-2 . Figure 11-2. CMOS Switch A cmos switch is instantiated as shown in Example 11-2 . Example 11-2 Instantiation of CMOS Switch cmos c1(out, data, ncontrol, pcontrol);//instantiate cmos gate. or cmos (out, data, ncontrol, pcontrol); //no instance name given. The ncontrol and pcontrol are normally complements of each other. When the ncontrol signal is 1 and pcontrol signal is 0, the switch conducts. If ncontrol signal is 0 and pcontrol is 1, the output of the switch is high impedance value. The cmos gate is essentially a combination of two gates: one nmos and one pmos. Thus the cmos instantiation shown above is equivalent to the following: nmos (out, data, ncontrol); //instantiate a nmos switch p mos (out, data, pcontrol); //instantiate a pmos switch Since a cmos switch is derived from nmos and pmos switches, it is possible to derive the output value from Table 11-1 , given values of data, ncontrol, and p control signals. 11.1.3 Bidirectional Switches N MOS, PMOS and CMOS gates conduct from drain to source. It is important to have devices that conduct in both directions. In such cases, signals on either side of the device can be the driver signal. Bidirectional switches are provided for this p urpose. Three keywords are used to define bidirectional switches: tran, tranif0, and tranif1. tran tranif0 tranif1 Symbols for these switches are shown in Figure 11-3 below. Figure 11-3. Bidirectional Switches The tran switch acts as a buffer between the two signals inout1 and inout2. Either inout1 or inout2 can be the driver signal. The tranif0 switch connects the two signals inout1 and inout2 only if the control signal is logical 0. If the control signal is a logical 1, the nondriver signal gets a high impedance value z. The driver signal retains value from its driver. The tranif1 switch conducts if the control signal is a logical 1. These switches are instantiated as shown in Example 11-3 . Example 11-3 Instantiation of Bidirectional 10 VNU-EPT SPEAKING TOPICS 2016 (1) Topic 1: The multi-level marketing (MLM) field is growing and its member companies are multiplying Should Vietnam’s government ban this business model? Give reasons and examples from your reading, experience or observations to support your point of view Topic 2: In Vietnam, the number of students violating traffic laws (no helmets, excessive passengers, underage driving, etc.) is increasing What is/are the most effective solution(s) to this social issue? Give reasons and examples from your reading, experience or observations to support your point of view Topic 3: In Vietnam, more and more cases of food safety violations have been reported in media, causing serious concerns for consumers Why does this problem still exist? Give reasons and examples from your reading, experience or observations to support your point of view Topic 4: Vietnam has a good variety of produce but imported produce is increasing while exports and domestic consumption are low As consumers, what can we to support Vietnamese farmers? Give reasons and examples from your reading, experience or observations to support your point of view Topic 5: Vietnam labor export has been a trend in Vietnam in recent years What are some major issues that (potential) laborers have to deal with and why these issues happen? Give reasons and examples from your reading, experience or observations to support your point of view Topic 6: How can we prevent child abuse (including physical abuse, emotional abuse, child labor, etc)? Give your opinion and support it with reasons and examples from your reading, experience or observations Topic 7: An increasing number of Vietnamese students are choosing self-supported education abroad Why you think this is currently a trend in Vietnam? Give your opinion and support it with reasons and examples from your reading, experience or observations Topic 8: Cyber-bullying is becoming popular in our society What are the reasons for this social issue? Give your opinion and support it with reasons and examples from your reading, experience or observations Topic 9: Big cities tend to be chosen by criminals from other places How can residents in these cities protect themselves against these dangerous criminals? Give your opinion and support it with reasons and examples from your reading, experience or observations Topic 10: Vietnam has been witnessing an imbalanced labor distribution: more and more people have been moving to urban areas for work while rural areas have been increasingly abandoned How can this problem be solved? Give your opinion and support it with reasons and examples from your reading, experience or observations The multi-level marketing (MLM) field is growing and its member companies are multiplying Should Vietnam’s government ban this business model? Give reasons and examples from your reading, experience or observations to support your point of view The multi-level marketing (MLM) field is growing and its member companies are multiplying Although this business model is quite popular in some countries, when coming to Vietnam, it seems to disguise in a complex way and causes many uncontrollable risks In my opinion, MLM should be banned in Vietnam due to several reasons Firstly, many swindlers use this method to take a huge amount of money from gullible people There have been a number of people, most of which are students and people in rural area, being swindled The MLM companies told them that they can earn huge profits from joining their system called pyramid scheme They use all of their money; some even borrow money or mortgage their properties to buy a lot of products But instead of earning huge profits, the MLM companies suddenly disappear and the innocent people have to face with big consequences Secondly, people who join the pyramid schemes of MLM companies may receive more losses than benefits The consumers become free employees of those companies advertising, selling 10 VNU-EPT SPEAKING TOPICS 2016 (2) Topic False idolization - regarding somebody as a hero with blind adoration or devotion – can cause embarrassment or even anger when an idolized person turns out not to be a real idol What are some reasons for false idolization and how to stop it? Give reasons and examples from your reading, experience or observations to support your point of view Topic A report by UNEP (United Nations Environment Programme) states that human populations have been over-exploiting the Earth’s natural resources by unsustainable development As a developing country, Vietnam has also been undergoing unsustainable development Discuss some major causes and effects of this social issue in the context of Vietnam Give reasons and examples from your reading, experience or observations to support your point of view Topic In Ho Chi Minh City, a recent ban on after-school tutoring which leads to job dismissals for violations has caused a lot of discussion nationwide Are you for or against this ban? Why? Give reasons and examples from your reading, experience or observations to support your point of view Topic With the development of technology, Internet fraud is increasingly popular all over the world Discuss some major cases in Vietnam recently and some solutions to prevent it Give reasons and examples from your reading, experience or observations to support your point of view Topic Some countries apply humane punishments for prisoners by giving them certain facilities in prison Other countries insist that prisoners be punished severely by minimizing basic living conditions during their time there Do you think prisons should be a decent enough or a harsh environment? Why? Give reasons and examples from your reading, experience or observations to support your point of view Topic In Vietnam, a new traffic law taking effect on August 1st, 2016 imposes the same fine on people who go through the red light and the yellow light Do you agree or disagree with this new rule? Why? Give your opinion and support it with reasons and examples taken from your reading, experience, or observations Topic In Vietnam, a number of reality shows for children, especially music contests, appear to have adult content: children singing adult songs, wearing too much makeup, etc Do you think it is normal or inappropriate? Why? Give your opinion and support it with reasons and examples taken from your reading, experience, or observations Topic Should Vietnam have more public holidays or longer holidays? Why? Give your opinion and support it with reasons and examples taken from your reading, experience, or observations Topic 9: Should the time for Vietnamese university education be shortened to 3-4 years instead of 4-6 years like before? Why? Give your opinion and support it with reasons and examples taken from your reading, experience, or observations Topic 10: More and more Vietnamese parents send their children abroad for high school education as early as 15 years of age Do you agree or disagree with this decision? Give your opinion and support it with reasons and examples taken from your reading, experience, or observations False idolization - regarding somebody as a hero with blind adoration or devotion – can cause embarrassment or even anger when an idolized person turns out not to be a real idol What are some reasons for false idolization and how to stop it? Give reasons and examples from your reading, experience or observations to support your point of view Introduction: Nowadays, many people, especially teenagers, are regarding their favorite singers or actors as perfect idols And when their idols turn out to be not perfect, they become angry and bad things Reasons: I think there are some reasons for this problem: - Firstly, teenagers nowadays are strongly affected by TV and movies When the actor plays a good character in the movie, teenagers believe that he is also a perfect person in real life like his character So,