承载比试验制件方法探讨

现行规范中规定 ,承载比 (CBR)试验试件制备采用锤击法 ,文中结合实践 ,介绍另一种制备试件方法———静压法 ,并探讨其可行性。

利用自制环刀制作冻土三轴试件

冻土的力学试验中,因原状冻土有一定结构性,是重塑土无法替代的。因此制备出原状冻土试件的质量与速度关系到整个冻土力学试验结果的准确性与研究效率。本文介绍一种制备原状冻土三轴试件方法。此方法制备出的试件规格统一,且制件速度比传统方法高很多。同时也指出此制备方法的适用条件。

Ciona intestinalis as an emerging model organism: its regeneration under controlled conditions and methodology for egg dechorionation

The ascidian Ciona intestinalis is a model organism of developmental and evolutionary biology and may provide orucial clues concerning two fundamental matters, namely, how chordates originated from the putative deuterostome ancestor and how advanced chordates originated from the simplest chordates. In this paper, a whole-life-span culture of C. intestinalis was conducted. Fed with the diet combination of dry Spirulina, egg yolk, Dicrateria sp., edible yeast and weaning diet for shrimp, C. intestinalis grew up to average 59 mm and matured after 60 d cultivation. This culture process could be repeated using the artificially cultured mature ascidians as material. When the fertilized eggs were maintained under 10, 15, 20, 25 ℃, they hatched within 30 h, 22 h, 16 h and 12 h 50 min respectively experiencing cleavage, blastulation, gastrulation, neurulation, tailbud stage and tadpole stage, The tadpole larvae were characterized as typical but simplified chordates because of their dorsal nerve cord, notochord and primordial brain. After 8-24 h freely swimming, the tadpole larvae settled on the substrates and metamorphosized within 1-2 d into filter feeding sessile juvenile ascidians. In addition, unfertilized eggs were successfully dechorionated in filtered seawater containing 1% Tripsin, 0.25% EDTA at pH of 10.5 within 40 min. After fertilization, the dechorionated eggs developed well and hatched at normal hatching rate. In conclusion, this paper presented feasible methodology for rearing the tadpole larvae of C. intestinalis into sexual maturity under controlled conditions and detailed observations on the embryogenesis of the laboratory cultured ascidians, which will facilitate developmental and genetic research using this model system.

Development of New Generation Catalysts for Selective Hydrodesulfurization of FCC Naphtha

The influence of active metal components of catalyst, additives and catalyst preparation method on the reactivity of catalyst for selective hydrodesulfurization (HDS) of FCC naphtha was investigated, and the RSDS-21 catalyst with high HDS performance and the RSDS-22 catalyst with high selectivity were developed by RIPP. The composite loading of a new series of catalysts for selective HDS of FCC gasoline has demonstrated excellent desulfurization activity and selectivity and can under conventional hydrotreating conditions manufacture clean gasoline product meeting the national IV emission standard and the Euro V emission standard with less loss in antiknock index. The finalized new series of FCC catalysts upon being adopted for selective HDS of FCC naphtha have good adaptability to different feedstocks along with good stability.

Black Pine Afforestations in Abruzzo （Central Italy）： Perspectives and Management

In Italy, the hydro-geological protection of the Apennine territories is a well-known issue. For this reason, at the end of the 19th century, a new reforestation technique was proposed by the Inspector of Forest Service, Pietro Montanari to cope with difficult soil conditions of the mountain areas. This new approach was the first application of the so-called ＂gradoni＂ （small terraces） method of soil preparation. Each ＂gradone＂ was 100-120 cm wide and made with a slight counter slope （ca 10-15 degrees） to promote the accumulation of water and organic matter. Along each ＂gradone＂, bare root black pine seedlings （Pinus nigra Am.） were planted at a distance of 1 m from each other with a density of more than 3,000/ha. Nowadays, 19,158 hectares of black pine forests are growing in the Apennine of the Abruzzi region, largely resulting from those reforestation projects realized since the beginning of the 20th century. A case study of Monte Plaia （42°00′ 12″ N 13°53′39″ E）, that illustrates the situation after 70-110 years in consequence of lacking of silvicultural treatment and the application of aforest restoration method is presented.

A Pseudo Random Number Generator under Windows Using Refined Descriptive Sampling

In this paper, we propose a software component under Windows that generates pseudo random numbers using RDS （Refined Descriptive Sampling） as required by the simulation. RDS is regarded as the best sampling method as shown in the literature. In order to validate the proposed component, its implementation is proposed on approximating integrals. The simulation results from RDS using ＂RDSRnd＂ generator were compared to those obtained using the generator ＂Rnd＂ included in the Pascal programming language under Windows. The best results are given by the proposed software component.

Control method for semi-active suspension based on virtual prototype

The simple dynamic model is often adopted to deal with control questions in research on semi-active suspension. The model has more theoretic meanings than authentic ones because of difference between practical and physical models. The virtual prototype has remarkable advantages in its application simulation processes. It is not only faster and more veracious, but also of better visualization of the simulation results.

A simulation of diesel hydrotreating process with real component method

Computer simulation is a good guide and reference for development and research on petroleum refining processes. Traditionally, pseudo-components are used in the simulation, in which their physical properties are estimated by empirical relations and cannot be associated with actual chemical reactions, as no molecular structure is available for pseudo-components. This limitation can be overcome if real components are used. In this paper, a real component based method is proposed for the simulation of a diesel hydrotreating process by using the software of Unisim Design. This process includes reaction units and distillation units. The chemical reaction network is established by analyzing the feedstock. The feedstock is characterized by real components, which are obtained based on true boiling point curve. Simulation results are consistent with actual data.

Institutional Distance and CrossNational Income Gaps

ihis paper examines the root causes of current cross-national institutional difference from the perspective of national hetereogeneity and provides detailed explanations on the justification and effectiveness of using cross-national genetic distance as the instrumental variable （IV） of institutional difference. We combined 10,585 samples by pairing 146 countries and regions, created a cross-national institutional distance variable composed of 14 indicators from the World Bank and the Heritage Foundation in three aspects including differences of political system, economic system and institutional implementation attributes, and conducted a cross-section IV estimation for the long-term effect of institutional differences on cross-national income gaps using data between 1996 and 2010. Empirical results indicate that institutional difference has a long-term significant positive effect on cross-national income gaps and such an effect has a tendency to increase during sample period. With factors like human capital, geographical factor, language and religion under control, we still arrived at similar conclusions. The empirical results are demonstrated to be robust using different genetic distance measurement indicators and estimation methods.

A Study on Preconditions Setting of Long-Term Contract between Manufacturer and Component Supplier

To provide a risk-sharing mechanism that encourages a component supplier and a manufacturer to expand their production capacity of components and products, many researches on SCM suggested that it is better for the SC players to connect a long-term contract with flexible preconditions before doing the decision-making of production capacity. With considering of the uncertainty of demand and integrity problems between SC players, it is difficult to set reasonable preconditions. As a result, under-investment problems still occur frequently. In this paper, after we had discussed the decision-making of production capacity with the preconditions by analyzing the character of the players, we verified the under-investment problem of the supply chain. In order to clarify the optimum preconditions to alleviate the under-investment problem, we also analyzed the relations between preconditions and supply capacity of the whole supply chain. In the last part of this paper, we proposed a method of preconditions setting in such uncertain situations.

Study on the large-scale assembly and fabrication method for SWCNTs nano device

The large-scale assembly and fabrication method for single-walled carbon nanotube(SWCNT) nano devices was implemented.Assembly of SWCNT field effect transistor(FET) was realized by floating potential dielectrophoresis approach.The simulation of floating potential distribution of the chip was performed by comsol multiphysics coupling software.Six hundred devices were assembled on the area of less than one square centimeter.The fabricated devices were characterized by atomic force microscopy and scanning electron microscopy.The experimental results showed that large-scale assembly had been realized,and the success rate of ideal assembly for SWCNT FET had been assessed.

Discrete-Time Mean-Field Stochastic H_2/H_∞ Control

The finite horizon H_2/H_∞ control problem of mean-field type for discrete-time systems is considered in this paper. Firstly, the authors derive a mean-field stochastic bounded real lemma(SBRL). Secondly, a sufficient condition for the solvability of discrete-time mean-field stochastic linearquadratic(LQ) optimal control is presented. Thirdly, based on SBRL and LQ results, this paper establishes a sufficient condition for the existence of discrete-time stochastic H_2/H_∞ control of meanfield type via the solvability of coupled matrix-valued equations.

COOPERATIVE CONTROL OF MULTI-AGENT MOVING ALONG A SET OF GIVEN CURVES

This paper deals with a cooperative control problem of a team of double-integrator agents moving along a set of given curves with a nominated formation. A projection-tracking design method is proposed for designing the path-following control and the formation protocol, which guarantee forma- tion motion of the multi-agent system under a directed communication graph. Necessary and sufficient conditions of the control gains for solving the coordinated problem are obtained when the directed communication graph has a globally reachable node. Simulation results of formation motion among three agents demonstrate the effectiveness of the proposed approach.

Fixture Variation Diagnosis of Compliant Assembly Using Sensitivity Matrix

An automotive body is composed of compliant sheet metal parts.Fast and exactly diagnosing variation sources is very important when assembly variations happen.This paper proposes a diagnosis method of multi fixture variations based on the variation model of compliant sheet metal assembly.The assembly variation model is obtained by using the method of influence coefficients(MIC) and considering the manufacturing variations of compliant parts and multi fixture variations.The measurement point variations induced by part manufacturing variations are firstly removed from the measurement data.The variation patterns of multi fixture variations are constructed by column vectors of fixture variation sensitivity matrix.This method is proved to be feasible for exactly diagnosing the fixture variations and has higher diagnosis efficiency than designated component analysis(DCA).

Characterization of the thermal conductivity of La0.95r0.05CoO3 thermoelectric oxide nanofibers

Thermoelectric oxide nanofibers prepared by electrospinning are expected to have reduced thermal conductivity when compared to bulk samples. Measurements of nanofibers＇ thermal conductivity is challenging since it involves sophisticated sample preparation methods. In this work, we present a novel method suitable for measurements of thermal conductivity of a single nanofiber. A microelectro- mechanical （MEMS） device has been designed and fabricated to perform thermal conductivity measurements on a single nanofiber. A special Si template was designed to collect and transfer individual nanofibers onto a MEMS device. Pt was deposited by a focused ion beam to reduce the effective length of a prepared nanofiber. La0.95r0.05CoO3 nanofibers with diameters of 140 run and 290 run were studied and characterized using this approach at room temperature. Measured thermal conductivities yielded values of 0.7W-m 1-K-1 and 2.1 W.m-I＇K-1, respectively. Our measurements in La0.95r0.05CoO3 nanofibers confirmed that a decrease of linear dimensions has a profound effect on its thermal conductivity.

Effects of first-order chemical reactions on the dispersion coefficient associated with laminar flow through the lungs

This paper aims to look into the determination of effective area-average concentration and dispersion coefficient associated with unsteady flow through a small-diameter tube where a solute undergoes first-order chemical reaction both within the fluid and at the boundary. The reaction consists of a reversible component due to phase exchange between the flowing fluid and the wall layer, and an irreversible component due to absorption into the wall. To understand the dispersion, the governing equations along with the reactive boundary conditions are solved numerically using the Finite Difference Method. The resultant equation shows how the dispersion coefficient is influenced by the first-order chemical reaction. The effects of various dimensionless parameters e.g. Da （the Damkohler number）, a （phase partitioning number） and F （dimensionless absorption number） on dispersion are discussed. One of the results exposes that the dispersion coefficient may approach its steady-state limit in a short time at a high value of Damkohler number （say Da 〉 10） and a small but nonzero value of absorption rate （say P 〈0.5）.