汉代“出行”风格墓葬壁画的内涵研究

汉代墓葬中的壁画向现代人展示了大汉王朝艺术的辉煌与繁荣,尤其是其中“出行”风格的壁画,为研究汉代社会发展状况提供了有力依据。壁画在中国美术史中具有极高的艺术地位,翔实生动的壁画图像让我们能够有机会去深入研究汉代美术的嬗变趋势和造型结构,了解西汉、东汉不同时期汉代墓葬笔画的艺术和特点。本文的研究结合考古学、美术学等相关学科内容,从文化背景、“出行”风格墓葬壁画类型划分、壁画嬗变、壁画造型与内涵等方面深入挖掘汉代“出行”风格墓葬壁画。本文所选取的多幅图片来自于不同时期的汉墓出土的壁画,西汉东汉兼具,力求完整呈现出两汉“出行”风格墓葬壁画的艺术演变规律和高超的美学特征。

解决山区农民“出行难”的公共服务路径

山区农民"出行难"是"三农"问题的具体体现,它不仅对山区农民生活、农村建设和农业发展产生负面影响,同时也反映出政府在向山区提供公共产品和公共服务中存在的弊端。解决山区农民"出行难"是承担着社会公共服务职能的政府的职责所在。政府只有努力提高其公共服务能力,在行政理念、公共财政和服务内容上充分体现对山区农民的服务性,这样才能逐步弥补政府对山区农村公共产品的长期供给不足,最终解决山区农民"出行难"问题。

城市轨道交通乘客智慧出行信息服务平台构建研究

以城市轨道交通为主的乘客智慧出行服务存在群体性服务多、增值服务内容单一等问题,在总结现有的城市轨道交通乘客服务和分析不同乘客出行需求的基础上,提出城市轨道交通乘客智慧出行信息服务平台的业务需求以及技术架构。以乘客画像模块为基础生成乘客的个性化标签,探讨出行诱导模块和增值服务模块的构建方法,将出行诱导信息和增值服务信息与乘客的个性化标签匹配,实现出行规划、出行诱导、广告匹配、服务推送等功能,最终达到全出行链服务、个性精准信息服务、多元化增值服务的目标,支撑新技术、新理念在未来轨道交通运营服务中的应用和实施。

Effect of interrupted aging on mechanical properties and corrosion resistance of 7A75 aluminum alloy

The effects of interrupted aging on mechanical properties and corrosion resistance of 7A75 aluminum alloy extruded bar were investigated through various analyses,including electrical conductivity,mechanical properties,local corrosion properties,and slow strain rate tensile stress corrosion tests.Microstructure characterization techniques such as metallographic microscopy,scanning electron microscopy(SEM),and transmission electron microscopy(TEM)were also employed.The results indicate that the tensile strength of the alloy produced by T6I6 aging is similar to that produced by T6I4 aging,and it even exceeds 700 MPa.Furthermore,the yield strength increases by 52.7 MPa,reaching 654.8 MPa after T6I6 aging treatment.The maximum depths of intergranular corrosion(IGC)and exfoliation corrosion(EXCO)decrease from 116.3 and 468.5μm to 89.5 and 324.3μm,respectively.The stress corrosion factor also decreases from 2.1%to 1.6%.These findings suggest that the alloy treated with T6I6 aging exhibits both high strength and excellent stress corrosion cracking resistance.Similarly,when the alloy is treated with T6I4,T6I6 and T6I7 aging,the sizes of grain boundary precipitates(GBPs)are found to be 5.2,18.4,and 32.8 nm,respectively.The sizes of matrix precipitates are 4.8,5.7 and 15.7 nm,respectively.The atomic fractions of Zn in GBPs are 9.92 at.%,8.23 at.%and 6.87 at.%,respectively,while the atomic fractions of Mg are 12.66 at.%,8.43 at.%and 7.00 at.%,respectively.Additionally,the atomic fractions of Cu are 1.83 at.%,2.47 at.%and 3.41 at.%,respectively.

Leaching behavior of metals from high-arsenic dust by NaOH-Na_2S alkaline leaching

Arsenic is selectively extracted from high-arsenic dust by NaOH-Na2S alkaline leaching process. In the leaching arsenic process, the effects of alkali-to-dust ratio, sodium sulfide addition, leaching temperature, leaching time and liquid-to-solid ratio on metals leaching efficiencies were investigated. The results show that the arsenic can be effectively separated from other metals under the optimum conditions of alkali/dust mass ratio of 0.5, sodium sulfide addition of 0.25 g/g, leaching temperature of 90 ℃, leaching time of 2 h, and liquid-to-solid ratio of 5：1 （mL/g）. Under these conditions, the average leaching efficiencies of arsenic, antimony, lead, tin and zinc are 92.75%, 11.68%, 0.31%, 29.75% and 36.85%, respectively. The NaOH-Na2S alkaline leaching process provides a simple and highly efficient way to remove arsenic from high-arsenic dust, leaving residue as a suitable lead resource.

Leaching behavior of metals from limonitic laterite ore by high pressure acid leaching

The leaching behavior of metals from a nickeliferous limonitic laterite ore was investigated by high pressure acid leaching process for the extraction of nickel and cobalt.The effects of sulfuric acid added,leaching temperature,leaching time and liquid/solid（L/S） ratio on metals extraction were examined.More than 97% Ni,96% Co,93% Mn,95% Mg and less than 1% Fe are extracted under optimum conditions.Analysis of the high pressure acid leaching residue by chemical and XRD analysis indicates that the residual iron and sulfur are mainly present in phases of hematite and alunite,respectively.The high pressure leaching process provides a simple and efficient way for the high recovery of nickel and cobalt from laterite ore,leaving residue as a suitable iron resource.

Effect of aging time on precipitation behavior, mechanical and corrosion properties of a novel Al-Zn-Mg-Sc-Zr alloy

The precipitation behavior, mechanical properties and corrosion resistance of a novel Al-Zn-Mg-Sc-Zr alloy aged at different time were studied by optical microscopy（OM）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, tensile tests, potentiodynamic polarization and electrochemical impedance spectroscopy. The results revealed that with increasing aging time at 120 ℃, the hardness and tensile strength of the alloy increased rapidly at first and then slightly decreased. The resistance of exfoliation corrosion（EXCO） and intergranular corrosion（IGC） increased gradually with increasing aging time. The same trend of corrosion properties was demonstrated by electrochemical polarization curves and EIS test. The characteristics of grain boundary precipitates and precipitate free zone（PFZ） had a significant influence on the mechanical and corrosion behaviors of the studied alloy. On the basis of TEM observations, the size of grain boundary precipitates and the width of PFZ became larger, and the distributed spacing of grain boundary precipitates was enhanced with increasing aging time.

Effects of external stress aging on morphology and precipitation behavior of θ'' phase in Al-Cu alloy

The exposure of Al-5Cu alloy to an external stress with normal aging was carried out. The effects of external stress-aging on the morphology and precipitation behavior of θ＂ phase were investigated by transmission electron microscopy （TEM）, differential scanning calorimetry （DSC） and first principle calculation. The size of the θ＂ phase precipitated plates in stress-aging （453 K, 6 h, 50 MPa） is 19.83 nm, which is smaller than that of those present （28.79 nm） in stress-flee aging （453 K, 6 h）. The precipitation process of θ＂ phase is accelerated by loading external stress aging according to the analysis of DSC results. The apparent activation energy for the external stress-aging is 10% lower than the stress-free one. The first principle calculation results show that the external stress makes a decrease of 6% in the interface energy. The effects of the stress on aging process of the alloy are discussed on the basis of the classical theory. The external stress changes the morphology and precipitation behavior of θ＂ phase because the critical nucleation energy is decreased by 19% under stress aging.

Atmospheric oxygen-rich direct leaching behavior of zinc sulphide concentrate

The leaching behavior of main metallic sulphides in zinc concentrate under atmospheric oxygen-rich direct leaching conditions was studied through mineralogical analysis. The results show that the sulphides dissolve obviously except pyrite. Based on the relationship between elemental sulfur and the residual sulphides in the leaching residue, the dissolution of sphalerite, chalcopyrite, covellite and galena is assumed to follow the indirect oxidation reactions, where the acidic dissolution takes place firstly and then the released H2S transfers from the mineral surface into bulk solution and is further oxidized into elemental sulfur. The interface chemical reaction is further supposed as the controlling step in the leaching of these sulphides. The direct electrochemical oxidation reactions are assumed to contribute to the dissolution of pyrrhotite, which is controlled by the diffusion through elemental sulfur layer.

Influence of land use characteristics and trip attributes on commuting mode choice: a case of Nanjing

The effects of socio-demographics, land use characteristics and trip attributes on the commute mode choice are studied with a nested logit （NL） model. Based on the random utility maximum theory, the NL model is formulated. The analysis is carried out in the main area of Nanjing. Direct and cross elasticities are calculated to analyze the effects of travel time and travel cost on the selection of travel mode choice. The results reveal that the non-motorized travel modes are more attractive in the areas with higher housing and employment accessibility and car owners are found to be more likely to commute to work by car. The bus and subway choice probabilities are more sensitive to changes in travel times than to changes in travel costs. In conclusion, a comprehensive public transit system and effective integration of land use and transportation policies help to relieve the traffic congestion levels caused by the increasing urban sprawl.

Modeling customer satisfaction for bus rapid transit in Changzhou, China

This paper aims to develop a customer satisfaction model for bus rapid transit （BRT）. Both the socio-economic and travel characteristics of passengers were considered to be independent variables. Changzhou BRT was taken as an example and on which on-board surveys were conducted to collect data. Ordinal logistic regression （OLR） was used as the modeling approach. The general OLR-based procedure for modeling customer satisfaction is proposed and based on which the customer satisfaction model of Changzhou BRT is developed. Some important findings are concluded： Waiting sub-journey affects customer satisfaction the most, riding sub- journey comes second and arriving station sub-journey has relatively fewer effects. The availability of shelter and benches at stations imposes heavy influence on customer satisfaction. Passengers＇ socio-economic characteristics have heavy impact on customer satisfaction.

Modeling commuters' route choice behavior under pre-trip information system

Research about the auto commuter＇s pre-trip route choice behavior ignores the combined influence of the real-time information and all respondents＇ historical information in the existing documents.To overcome this shortcoming,an approach to describing the pre-trip route choice behavior with the incorporation of the real-time and historical information is proposed.Two types of real-time information are investigated,which are quantitative information and prescriptive information.By using the bounded rationality theory,the influence of historical information on the real-time information reference process is examined first.Estimation results show that the historical information has a significant influence on the quantitative information reference process,but not on the prescriptive information reference process.Then the route choice behavior is modeled.A comparison is also made among three route choice models,one of which does not incorporate the real-time information reference process,while the others do.Estimation results show that the route choice behavior is better described with the consideration of the reference process of both quantitative and prescriptive information.

Application of support vector machine in trip chaining pattern recognition and analysis of explanatory variable effects

In order to improve the accuracy of travel demand forecast and considering the distribution of travel behaviors within time dimension, a trip chaining pattern recognition model was established based on activity purposes by applying three methods： the support vector machine （SVM） model, the radial basis function neural network （RBFNN） model and the multinomial logit （MNL） model. The effect of explanatory factors on trip chaining behaviors and their contribution to model performace were investigated by sensitivity analysis. Results show that the SVM model has a better performance than the RBFNN model and the MNL model due to its higher overall and partial accuracy, indicating its recognition advantage under a smai sample size scenario. It is also proved that the SVM model is capable of estimating the effect of multi-category factors on trip chaining behaviors more accurately. The different contribution of explanatory, factors to trip chaining pattern recognition reflects the importance of refining trip chaining patterns ad exploring factors that are specific to each pattern. It is shown that the SVM technology in travel demand forecast modeling and analysis of explanatory variable effects is practical.

Combined model of trip mode and destination

This paper analyzes the characteristics of the destination distribution of trips and proposes a stratified sampling strategy for travel mode choice.The stratified sampling strategy can reduce the size of the alternative set;thus,the computation burden of simulation is decreased.Using the stratified sampling strategy,a combined choice model of the trip mode and destination is developed based on the Bayesian theory.Simulations are carried out to verify the proposed model.The results show that the combined choice model of the trip mode and destination can efficiently simulate travelers＇ choice behaviors.Furthermore,the forecasting accuracy of the combined choice model is higher than the one of the gravity model.Therefore,the proposed model is a powerful tool with which to analyze travelers＇ behaviors in selecting the trip mode.

Effect of moderately thermophilic bacteria on metal extraction and electrochemical characteristics for zinc smelting slag in bioleaching system

The effects of moderately thermophilic bacteria on the extraction of metals from zinc smelting slag and electrochemical characteristics of zinc smelting slag carbon paste electrode in bioleaching process were studied. The results show that the extraction rates of Fe, Cu and Zn from the slag reach 86.7%, 90.3% and 66.7% after adsorbed bacteria sterilize, while those with adsorbed bacteria are 91.9%, 96.0% and 84.5% in conditions of pulp density 2%, pH 1.0, temperature 65 °C and stirring rate 120 r/min, respectively. Some stretching peaks of functional groups from bacterial secretes on the bioleached residue surface, such as 1007 cm-1 and 1193 cm-1, turn up through FI-IR analysis and indirectly reveal the presence of the adsorbed bacteria on the slag particles surface. Besides, the corrosion of zinc smelting slag is enhanced by bacteria according to the characteristics of cyclic voltametry and Tafel curves in bioleaching system.

Investigation on transformation process of trip mode choice for planned special events

This paper aims to provide a decision-making method for the transportation management strategies in guiding the transformation of trip mode choice during planned special events. The Expo 2010 Shanghai is taken as an example, and a structural equation model is employed to analyze the dynamic mechanism of trip mode choice behavior and the effectiveness of the transportation management measures at different stages. Based on the difference between the objective-oriented stated preference （SP） survey results and the objectives, together with the feedback from the previous stage survey, some adjustments on the transportation management measures are made in the next stage of the planning process until the objectives are eventually achieved. The results indicate that the adjustments on transportation management measures at different stages can effectively raise the transit share to 88.6%. Nonlocal visitors are inclined to choose nonstop modes of transportation and the companion attributes have the most significant effects on the trip mode choices of visitors. The research method is proved to be an effective way to support the decision making process of transportation management measures during planned special events in the future.

Uplink capacity analysis of single-user SA-MIMO system

A novel framework of which combines smart antennas multiple antenna systems, （SA） with multiple-input multiple-output （MIMO） at the receiver, is proposed. The uplink SA-MIMO system is investigated. The joint optimization problem corresponding to the uplink capacity of the single-user SA-MIMO system is deduced. Then the closedform expression of the capacity is obtained in the case of equal power allocation and the same direction-of-arrivals （DOAs） from different transmit antennas at the same antenna array, and an upper bound of the capacity is also given in the case of different DOAs at the same antenna array. After that, for the general case, a suboptimal method for the capacity optimization problem is presented. Some numerical results are also given to compare the capacities of conventional MIMO and SA-MIMO systems and show that the proposed method is viable.

SIMULATION STUDY OF CHAOS IN DC-DC CONVERTER

A DC DC buck converter c on trolled by naturally sampled, constant frequency PWM is considered. The existe nce of chaotic solutions and the output performance of the system under differen t circuit parameters are studied. The transforming pattern of system behavior fr om steady state to chaotic is discovered by the cascades of period doubling bi furcation and the cascades of periodic orbit in V I phase space. Accordingl y, it is validated that change of values of the circuit parameters may lead DC DC converter to chaotic motion. Performances of the output ripples fro m steady state to chaotic are analyzed in time and frequency domains respective ly. Some important conclusions are helpful for opt imization design of DC DC converter.

Electrochemical corrosion of Sn-0.75Cu solder joints in NaCl solution

The corrosion behaviors of Sn-0.75Cu solder and Sn-0.75Cu/Cu joint in 3.5% NaCl（mass fraction） solution were studied by potentiodynamic polarization test and leaching measurement.The polarization curves indicated that the corrosion rate of Sn-0.75Cu solder was lower than that of Sn-0.75Cu/Cu joint.The morphology observation and phase composition analysis on the corroded product at each interesting potential suggested that Sn3O（OH）2Cl2 formed on the surface of Sn-0.75Cu solder at active dissolution stage.As the potential increased from active/passive transition stage,all the surface of Sn-0.75Cu solder was covered by the Sn3O（OH）2Cl2 and some pits appeared after the polarization test.Compared to the Sn-0.75Cu solder alloy,much more Sn3O（OH）2Cl2 formed at active dissolution stage and the pits with bigger size were observed after polarization test for the Sn-0.75Cu/Cu solder joints.The leaching test confirmed that the faster electrochemical corrosion rate resulted in the larger amount of Sn released from the Sn-0.75Cu/Cu solder joints.

Effect of ammonium chloride on leaching behavior of alkaline anion and sodium ion in bauxite residue

This study focused on leaching behavior of alkaline anion and sodium in bauxite residue through ammonium chloride treatment.The results showed that the pH of bauxite residue decreased from 10.49 to 8.93,total alkaline anion(HCO3^-,CO3^2-,OH^-,AlO2^-)concentration reduced from 38.89 to 25.50 mmol/L,leaching rate of soluble sodium was 80.86%with ammonium chloride addition of 0.75%,liquid/solid(L/S)ratio of 3(mL/g),temperature of 30°C and reaction time of 18 h;L/S ratio was the main factor affecting the removal of alkaline anion and the leaching of sodium.Furthermore,ammonium chloride promoted the dissolution of diaspore and changed the micro/morphological characteristics with the increase of massive structure.The findings of this work will contribute to achieve soil-formation of bauxite residue.