Particle Production in Proton-Proton and Deuteron-Gold Collisions at RHIC

We try to understand recent data on proton-proton and deuteron-gold collisions at RHIC, employing a parton model approach called EPOS.Comment: Invited talk, given at SQM2004, Cape Town, South Africa, 15-20 September, 200

Theoretical investigation of SOFC/SOEC degradation mechanisms and mitigations

America has a rapid growth in the development of renewable power generation in the twenty-first century. Hydrogen energy especially is the major topic in development of renewable power generation because it has the ability to provide for energy in transportation, combined heat and power generation and energy storage systems with little or no impact on the global ecosystem. Electrolysis and fuel cell technology for hydrogen energy storage has brought interest to the researchers worldwide. Solid oxide electrolysis cells (SOECs) and Solid oxide fuel cells (SOFCs) are promising hydrogen energy technologies that can utilize chemical energy to produce and store electricity. SOEC can produce hydrogen at a higher chemical reaction rate with a lower electrical energy requirement. SOFCs offer significant advantages in the variety of fuels, quiet operation, low or zero emission and high efficiency. The performance of SOECs and SOFCs is the key for commercializing SOECs and SOFCs. This work presents the methods and theory of improving the performance of SOECs and SOFCs. A thermodynamic and electrochemical equilibrium model is established for SOECs by considering a cathode/electrolyte interfacial porous layer. By using numerical experiments, the one dimensional thermodynamic and electrochemical equilibrium model with porous layer provides a guideline for designing and optimizing SOECs. The mechanisms of SOFCs degradation are reported and the ideal maximum oxygen partial pressure is calculated to avoid SOFCs degradation

THE LIFT COMPONENT PRODUCED BY THE UPPER LIMBS DURING THE BREAST STROKE

It is known that a breaststroke swimmer's speed varies during a stroke cycle. Immediately after the leg drive (see Figure 1) the swimmer experiences a negative acceleration (-a) phase because the water resistance (R)is temporarily greater than the propulsive forces generated by the swimmer. This is followed by a phase of positive acceleration produced by the forces generated by the upper limbs. The purpose of this study was to determine the relative contributions of the lift and drag components of the forces produced by the upper limbs in causing the observed positive accelerations of the body. It was assumed that the lift component would be the greatest during lateral limb movements and that the drag component would be the greatest during backward limb movements. It was also assumed that the greatest positive acceleration of the swimmer would occur during the time of greatest positive tangential force production by the limbs (re. Newton's Second Law). A positive tengential force is one that acts in the same direction as the movement of the SWimmer's bedy and that has a magitude greater than that of the resistive forces opposing the body's motion

Make a living: agriculture, industry and commerce in Eastern Hebei, 1870-1937

The existing scholarship on Chinese agricultural history and peasant economy always portrayed Chinese peasants as cultivators and equated agricultural commercialization as cash crop growing. Based on the field surveys made by the Chinese and Japanese investigators in the 1930s, this dissertation tries to correct the over-simplification of the Chinese peasant economy and describe how the peasants in Eastern Hebei made a living by a combination of agriculture, industry and commerce. By examining the ecosystem and calculating the grain production and consumption, it is found that the returns from farming were not even enough for the peasants own consumption. Eastern Hebei was a grain shortage area and the peasants there had to engage in non-farming activities to supplement their income and support their families.;Besides engaging in traditional sideline production, the peasants in Eastern Hebei took the opportunities provided by the development of domestic and international trade and produced on a large scale for outside markets. The bristle processing in Fengrun county, paper making in Qian-an county and handicraft weaving in Baodi county are selected to show the importance of rural industry in the peasant economy in Eastern Hebei. This study also finds that in the modern period, either forced by survival pressure or attracted by outside opportunity, more and more peasants in Eastern Hebei left their villages and found temporary or permanent jobs in the outside world. The causes and consequences of the large scale emigrating- going to Manchuria - are discussed in detail to show the importance of non-farming income in the peasant economy.;The 1930s witnessed increases in state taxation, the civil war, the Japanese invasion and the world economic depression. These developments are discussed in terms of impact upon the peasants of the villages under consideration. It is found that it was harder for the peasants to make a living in that period. In conclusion, this study supports Fei Xiaotong\u27s argument that it was impossible for Chinese peasants to make a living on farming alone and the final solution forChina\u27s agrarian problem was diffused rural industrialization

Dynamic Response of Flexible Foundations on Multilayered Medium

The dynamic response of flexible strip-foundations placed on a viscoelastic multi-layered medium under conditions of plane strain and subjected to harmonic excitation is studied in this paper. A semi-analytic model is developed to determine the dynamic flexibility matrix of the medium, and the spline finite element method is employed to treat the foundation. The two methods are appropriately combined through equilibrium and compatibility considerations at the soil-foundation interface. Numerical results describing the influence of the non-homogeneity of the soil medium on the compliance are presented, and the effects of the relative stiffness Kr on the foundation response are briefly discussed