Multilayered Plate Model with “Adaptive” Representation of Displacements and Temperature Across the Thickness and Fixed D.O.F.

A new multilayered zig-zag plate model for analysis of thermo-elastic problems is developed. It a priori fulfils the boundary conditions and the stress contact conditions on interlaminar shear and normal stresses and the continuity of the heat flux and temperature at the layer interfaces, as prescribed by the elasticity theory and heat conduction equation. The functional d.o.f. are the mid-plane displacements and shear rotations, like for classical plate models, and the temperature at the upper and lower bounding faces. A non-classical feature, a high-order piecewise variation of the transverse displacement is assumed across the thickness aimed at accurately describing the transverse normal stress, as it has a significant bearing for keeping equilibrium in thermo-elastic problems. Also non classical feature, the representation of displacements and temperature can be different from point to point across the thickness, to adapt to the variation of solutions. This refinement is obtained by keeping the number of functional d.o.f. unchanged, since the coefficients of the hierarchic contributions are determined enforcing the fulfillment of the equilibrium and heat conduction equation at selected points across the thickness. As shown by the comparison with exact solutions of benchmark test cases, the present model accurately predicts displacement, stress and temperature variations across the thickness from constitutive equations, even when thickness is extreme and the thermo-elastic properties of layers are distinctly different. Its basic advantage over existing models is a lower computational effort under the same accuracy.     

Reachable Sets for the Heisenberg Sub-Lorentzian Structure On ℝ3. An Estimate for the Distance Function

In this paper we compute reachable sets from a point for the Heisenberg sub-Lorentzian metric on ℝ³ and give an estimate (from below) for the distance function. 2000 Mathematics Subject Classification. 53C50.     

How do oil price shocks affect the output volatility of the U.S. energy mining industry? The roles of structural oil price shocks

This paper focuses on how explicit structural shocks that characterize the endogenous character of international oil price change affect the output volatility of the U.S. crude oil and natural gas mining industries. To this end, we employ a modified structural vector autoregressive model (SVAR) to decompose real oil-price changes into four components: U.S. supply shocks, non-U.S. supply shocks, aggregate demand shocks, and oil-specific demand shocks mainly driven by precautionary demand. The results indicate that output volatility of the U.S. crude oil and natural gas mining industry has significantly negative responses to U.S. supply shocks, aggregate demand shocks, and oil-specific demand shocks, while lacks significant response to non-U.S. supply shocks. Variance decomposition and historical decomposition confirm that U.S. supply shocks occupy most explaining variations in output volatility among the four structural oil shocks. Moreover, the oil-specific demand shocks explain more variation than that of aggregate demand shocks for the crude oil mining industry, but the opposite is true for the natural gas mining industry.     

美国西部地热电力计划（Geopowering the West, Getting Organited in the Public Sector to Promote U. S. Geothermal Development, Roger Hill, GRC Bulletin Votl. 33, No. 2,March／Apr. 2994,63-66）

让西部用上地热电力(GPW)的倡议从2000年1月开始，一直致力于把西部有志于地热的团体和个人组织起来，成为州的地热开发、工作队伍。加利福尼亚和内华达是地热电力生产和基础设施方面的先导，西部其余各州对地热开发的雄心现在也得益于GPW的影响。倡议的目的是要把地热发电传送给西部的几百万家庭和企事业单位，建立公方与私方的伙伴关系。     

Comparison of the evolution of energy intensity in Spain and in the EU15. Why is Spain different?

Energy intensity in Spain has increased since 1990, while the opposite has happened in the EU15. Decomposition analysis of primary energy intensity ratios has been used to identify which are the key sectors driving the Spanish evolution and those responsible for most of the differences with the EU15 energy intensity levels. It is also a useful tool to quantify which countries and economic sectors have had most influence in the EU15 evolution. The analysis shows that the Spanish economic structure is driving the divergence in energy intensity ratios with the EU15, mainly due to strong transport growth, but also because of the increase of activities linked to the construction boom, and the convergence to EU levels of household energy demand. The results can be used to pinpoint successful EU strategies for energy efficiency that could be used to improve the Spanish metric.     

Thermochemical hydrogen preparation—Part V. A feasibility study of the sulfur iodine cycle

A sulfur-iodine cycle consists of the following three reactions:

$\text{2H}{}_2\text{O + SO}{}_2\text{+ I}{}_2\text{→ H}{}_2\text{SO}{}_4\text{+ 2HI,}$

$\text{H}{}_2\text{SO}{}_4\text{→ H}{}_2\text{O + SO}{}_2\text{+}\text{1}\text{2O}{}_2\text{,}$

$\text{2 HI → H}{}_2\text{+ I}{}_2\text{.}$

It was found that the first reaction can be performed as a cell reaction without the addition of external energy. The sulfuric acid and the hydriodic acid are produced separately in the anode and cathode compartments, respectively. The second and third reactions can be carried out as catalytic thermal decompositions. A process flow sheet of this cycle and its mass balance was based on experimental results, and the heat balance for this cycle was made. It was found that internal heat exchange for this cycle was very large (about 2600 kcal/mol H₂), due mainly to the low yield of the decomposition reaction of hydrogen iodide. Theoretical and experimental studies were made to improve the yield of this reaction. The following three methods seem to be promising for this purpose: (1) continuous removal of the hydrogen produced in the reaction zone; (2) performance of the reaction at low temperature (185–250°C) and high pressure (100 atml; and (3) substitution of the benzene-cyclohexane cycle (6HI ? C₆H₆ → C₆H₁₂ + 3I₂; C₆H₁₂ → C₆H₆ ? 3H₂) for the hydrogen iodide decomposition step.     

KT ENG.Co.,Ltd.

Introduction KT ENG.CO., LTD is manufacturing educational and vocational equipment in the Refrigeration ＆ Air-conditioning field for the Technical High School, College and University. Our products are Air Handling Unit trainer （KTE-1000AHU）, Standard Refrigeration Trainer （KTE-1000BA）, Temperature, Pressure ＆ Defrost Control Refrigeration Trainer （KTE-1000TP）, Refrigerant Parallel Expansion Refrigeration Trainer（KTE- 2000EV）, Evaporation Pressure Parallel Control Trainer（E.P.R Control） （KTE-2000EP）, 4-Way Reverse Valve Control Heat Pump Heating ＆ Cooling Trainer （KTE-3000HD）,     

水电厂智能控制.维护.管理集成系统

水电厂智能控制·维护·管理集成系统李朝晖叶鲁卿（华中理工大学，武汉，４３００７４）改革开放以来随着我国电力工业高速发展，电力企业的运行管理机制发生了深刻的变化．无人值班少人值守、安全可靠、经济高效已成为现代电力企业最重要的考核指标．目前的控制系统、维...     

关于“S.A.E.”的正确译名问题

“S.A.E.”的原文全文为:“Society fo Automotive Engineers”。长期以来,国内有下列三种译法:①美国汽车工程师学会,②美国自动车工程师学会,③美国机动车工程学会最近,作者赴美参加了在底特律举行,1989年S.A.E.国际会议和展览会。发现上述三种译法都有两个错误:     

Impact of H.I. Schlesinger's discoveries upon the course of modern chemistry on B−(N−)H hydrogen carriers

Representatives of B?(N?)H hydrogen carriers are alkali borohydrides (e.g. LiBH₄ and NaBH₄) and amine boranes (e.g. NH₃BH₃ and NaNH₂BH₃). These are old compounds; they were discovered in the first half of the 20th century. One of the main contributors to their development is Prof. Hermann I. Schlesinger (1882–1960). In the recent years, there has been new interest in these old compounds as novel chemical H storage materials. Sodium borohydride NaBH₄ is a typical example. It was discovered by Schlesinger and collaborators in the 1950s. At that time it was found to be an attractive H₂ generator; owing to this property it reemerged in the early 2000s for on-board H₂ generation. Today, Schlesinger is commonly considered as the pioneer of NaBH₄ as hydrogen carrier but the impact of Schlesinger and collaborators' discoveries upon the course of modern chemistry on B?(N?)H hydrogen carriers is far more extensive … This is highlighted herein.     

Pd–Ag thin film membrane for H2 separation. Part 2. Carbon and oxygen diffusion in the presence of CO/CO2 in the feed and effect on the H2 permeability

The effect of CO and CO₂ on the performance and stability of Pd–Ag thin film membranes prepared by electroless plating deposition (EPD) was investigated, observing the presence of dissociation to carbon and oxygen which slowly diffuse in the membrane influencing also H₂ permeability. The effect of the two carbon oxides was investigated both separately and combined in the 400–450 °C temperature range over long-term cumulative experiments (up to over 350 h) on a membrane that already worked for over 350 h in H₂ or H₂–N₂ mixtures. An increase of the H₂ permeation flux was observed feeding only CO₂ in the range 10–20%. This effect was interpreted as deriving from the facilitated H₂ flux caused from oxygen diffusion (deriving from CO₂ dissociation) in the membrane. CO induces instead a partial inhibition on the H₂ flux deriving from the negative effect of CO competitive chemisorption as well as C diffusion in the membrane, which overcome the positive effect associated to oxygen diffusion in the membrane. Carbon and oxygen diffuse through the membrane with a rate two order of magnitude lower than hydrogen, and recombinate at the permeate side forming CO, CO₂ and CH₄ which amount increases with time-on-stream. The effect is reversible and not associated with the creation of cracks or defects in the membrane, as supported by leak tests.     

Co-liquefaction of Yatağan lignite and waste tire under catalytic conditions. Part 1. Effect of fresh tetraline and recycled tetraline on the conversion

In this study, the effect of solvent type and the solvent/solid ratio on the liquefaction of Mu?la-Yatagan lignite (YL) combined with waste tire (WT) under catalytic conditions investigated. Liquefaction experiments carried out the following conditions, a reaction temperature of 400°C, a catalyst concentration of 3%, solvent/solid ratio from 1/1 to 9/1, reaction time of 90 min, lignite/waste ratio of 1/1. In addition, mixing speed was 400 rpm, and the nitrogen gas pressure fixed at 30 bar. After the each of liquefaction experiments finished, the soluble products (SP) classified as preasphaltene (PAS), asphaltene (AS) and oil+gas (OG), by solvent extraction. Due to the optimum total conversion determined, fresh tetraline obtained as the most favorable solvent with 71.71%, for the liquefaction of YL with WT. However, the total conversion for recycling tetraline is 68.6%. According to the results, co-liquefaction of YL combined with WT using recycle solvent is the one way to offer, alternatively of using crude oil, producing SP for not crude oil, producing SP for not only fuel-oil production but also prefer chemical raw materials. With respect to the optimum oil+gas yield results, the most convenient solvent type and the solvent/solid ratio are the recycled solvent and its 3/1 ratio.     

Metallic structures subjected to cyclic loadings—II. A new approach to assess the steady state

This work concerns the assessment of the steady state for metallic structures under prescribed force and cyclic prescribed displacement. In part I, it was confirmed that the elastic analysis forecasts were not always reliable especially when the elastic follow-up phenomenon is significant and the stresses due respectively to the prescribed displacement and force have membrane parts in the same direction. Since the majority of the rules for the design of such structures are based on elastic analyses, their forecasts could be negatively affected when the above situations exist. To avoid such a risk, a new method is proposed. Its application needs at the most an elastoplastic analysis of the first cycle and does not necessitate splitting the stress field into primary and secondary parts. Comparison of the forecasts of the proposed method with a number of test results on various structures is also presented.