重视“宽进”,忽视“优出”——中等职业学校招生的瓶颈

我国职业教育还处在发展的初级阶段,社会对职业教育的认识还没有转变,虽然国家技工缺口很大,但中等职业学校招生还存在较大难度。职业学校招生难不仅与百姓对职业教育认识有关,也与通过"宽进"招来的学生不能"优出"有关。所以,要突破中等职业学校招生的瓶颈,必须要提高教学质量,提升办学内涵,让"宽进"的学生"优出"。

人力资本扩张与企业扩大进口——兼论“优进优出”高水平对外开放新格局构建

本文借助高校扩招这一高等教育改革政策,采用双重差分法更为准确地评估人力资本扩张对企业中间投入进口的因果效应。研究发现:(1)人力资本扩张有效提升了企业中间投入进口规模,规模增长主要源于进口种类的丰富和平均进口价值的提高。(2)人力资本通过提升劳动者技能水平及其带来的生产效率改善和“技能—资本”互补进而增加了企业对中间投入进口的需求。(3)人力资本扩张对资本品及加工贸易企业、外资企业和处于高等教育资源丰裕城市企业中间投入进口的促进作用更为突出。(4)人力资本扩张通过中间投入进口的“规模效应”和“质量效应”能够进一步优化企业的出口绩效。本文从促进对外贸易平衡发展的角度为我国高等教育改革取得的政策成效提供了重要的经验支持,对于推动形成“优进优出”高水平对外开放新格局也具有重要意义。

中国对外贸易的“优进优出”战略:基于产品质量与增加值率视角的研究

本文利用中国工业企业数据和海关数据的匹配数据库,基于Tobit、IV-Tobit等多种计量方案实证研究了进口产品质量提升对出口产品质量和出口国内增加值率的影响。研究发现:(1)总体来看,一般贸易进口产品质量显著提升了对应产品的出口质量,且在高、低研发强度企业及外资企业和民营企业均得到一致结果;高研发强度企业加工贸易进口产品质量有利于提升其出口产品质量,低研发强度企业则呈现负向影响。(2)无论是基于OECD成员国、“一带一路”倡议抑或反倾销调查分组还是针对高收入国家,一般贸易下进口产品质量均显著提升了同类产品的出口质量,但低收入国家则不显著。对加工贸易而言,来自非OECD国家和“一带一路”沿线国家进口产品质量会降低出口产品质量。(3)从影响机制看,不管是一般贸易还是加工贸易,进口产品质量梯度均对进口产品质量影响出口产品质量的促进作用形成正向调节效应;一般贸易下进口产品质量通过创新中介效应显著提升了出口产品质量;但加工贸易下该效应则不确定。(4)进一步拓展研究发现,一般贸易下进口产品质量显著提高了出口国内增加值率,但加工贸易却降低了国内出口增加值率。

在外贸新常态下推进我国外贸供给侧改革培育竞争新优势研究

在外贸新常态下我国外贸生产企业供需结构发生了变化,为了培育外贸在国际市场中新的竞争优势,需要对我国供给侧进行改革.在我国劳动力优势缩小、生产成本升高、外部需求乏力的情况下,用国际视野的眼光推进供给侧的改革,处理好对外商品出口和对内商品的进口,积极推动外贸方式创新,实现创新发展,推动外贸生产结构变革,向高端化、绿色化、服务化发展.

瓦斯非均衡赋存煤层精准冲孔增透技术及应用

为实现瓦斯非均衡赋存煤层的精准卸压增透,基于理论建模、数值模拟和现场试验的方法研究了水力冲孔关键工艺参数的判定准则和优化方法。构建了卸压煤层多场耦合模型,分析了冲孔最优出煤量的判定指标体系,提出了冲孔最优出煤量的判定准则及方法,绘制了水力冲孔关键工艺参数优化图谱,提出了瓦斯非均衡赋存煤层梯级精准增透强化抽采技术。结果表明:(1)抽采时间一定时,随着冲孔出煤量的增加,煤层残余瓦斯含量逐渐降低,而由于孔间应力集中程度的升高,残余瓦斯压力先降低后升高;(2)冲孔最优出煤量的判定准则包括瓦斯抽采达标约束和巷道失稳风险和施工成本最小化约束,当残余瓦斯含量和压力均小于临界值时,认为抽采达标,在满足抽采达标的前提下,应尽量减小冲孔出煤量以保证煤巷稳定、降低工程成本;(3)冲孔最优出煤量随地应力的升高而降低,随黏聚力、瓦斯压力和钻孔间距的增大而升高。对于给定煤层,冲孔出煤量存在最大值,抽采达标时间存在最小值;(4)综合考虑煤层瓦斯压力、出煤量、钻孔间距及抽采达标时间之间的关联关系,绘制了冲孔关键参数的优化图谱,提出了瓦斯非均衡赋存煤层梯级精准增透强化抽采技术,融合煤层瓦斯赋存特征和冲孔关键参数的优化图谱,确定不同瓦斯赋存区域对应的冲孔工艺参数,实现瓦斯非均衡赋存煤层的精准卸压增透。

Optimization of copper extraction for bioleaching of complex Cu-polymetallic concentrate by moderate thermophiles

Effects of initial pH, temperature, liquid volume, rotation speed, galvanic interaction （pyrite ratio） and pulp density on bioleaching of complex Cu-polymetallic concentrate were investigated. The results indicated that the copper extraction at pH 1.5 was 1.5 and 1.4 times that at pH 1.0 and pH 2.0 respectively. The copper extraction obtained at 45 ℃ was 1236.8%higher than that at 50 ℃. With the increase of rotation speed or the decrease of liquid volume, copper extraction was improved obviously. Copper extraction was improved gradually with the increase of pyrite ratio. However, when the ratio was higher than 20.0%, no further increase in copper extraction was observed. And the statistically significant interactive effects on copper extraction were found between temperature and pH, and temperature and pyrite ratio.

A Fully Integrated CMOS Readout Circuit for Particle Detectors

Novel schemes for a charge sensitive amplifier （CSA） and a CR-（RC）, semi-Gaussian shaper in a fully integrated CMOS readout circuit for particle detectors are presented. The CSA is designed with poly-resistors as feedback components to reduce noise. Compared with conventional CSA, the input referred equivalent noise charge（ENC） is simulated to be reduced from 5036e to 2381e with a large detector capacitance of 150pF at the cost of 0.5V output swing loss. The CR-（RC）,semi-Gaussian shaper uses MOS transistors in the triode region in series with poly-resistors to compensate process variation without much linearity reduction.

基于大偏差理论的随机动力学研究

本文介绍了大偏差理论的基本思想、基本概念以及大偏差理论在离出问题研究中的应用.本文评述了有关离出问题的三个重要指标:平均首次离出时间、离出位置分布和最优离出路径相关研究的思路和方法,而其中对最优离出路径的刻化是结构性的难题.针对平均首次离出时间,本文介绍了它与拟势的关系,并应用平均首次离出时间的结论分析了随机共振以及自诱导随机共振中的时间匹配机制.对于离出位置分布,本文介绍了提高蒙特卡罗模拟速度的相关算法,并重点评述了其中的概率演化算法和相关的算例.最后,对于最优离出路径的研究,本文讨论了几类计算方法,分析了最优路径满足的辅助哈密尔顿系统轨线由于非线性多值性形成的拉格朗日流形拓扑结构的奇异性及其动力学含义,并进一步给出了有限噪声强度激励条件下的作用量修正方法.最后,给出了大偏差理论应用发展的一些开放性问题的展望.

关于深化对外开放推进江苏高质量发展研究

1978年改革开放以来,随着与世界各国的贸易往来日益密切,由于劳动力、土地等要素的比较优势明显,江苏的对外贸易不断扩大,开放区域从无到有,从"引进技术",到"走出国门",从国际劳务工程承包到生产经营海外投资,出口产品结构不断优化,工业制成品比重大幅提高,使江苏的经济快速增长,国民生产总值不断提高。但在国际贸易环境的严峻挑战之下,还需进一步深化对外开放改革,提高国际竞争力,增强外贸发展新动能,使高新技术产品出口成为外贸发展的新增长点,推动对外贸易"优进优出",加快全方位宽领域多层次的开放型经济体系的形成。

离心流动超细粉碎机中粉碎球的运动特性

介绍了离心流动超细粉碎机的工作原理和特征,并由广义的运动微分方程推导出离心流动超细粉碎机中粉碎球的运动方程,进而总结出离心流动超细粉碎机设计中最重要的设计参数——最优抛出角0α的计算方法。为离心流动超细粉碎机的实际应用提供了理论基础与依据。

Optimization of operating parameters and kinetics for chloride leaching of lead from melting furnace slag

The feasibility and kinetics of lead recovery from the slag of traditional lead melting furnace using chloride leaching were investigated.The effects of operating parameters such as leaching time,NaCl concentration,FeCl3concentration,liquid/solid ratio,stirring rate,temperature,and particle size on recovery of lead were studied and the optimization was done through the response surface methodology(RSM)based on central composite design(CCD)model.The optimum conditions were achieved as follows:leaching time60min,80°C,stirring rate800r/min,NaCl concentration200g/L,FeCl3concentration80g/L,liquid/solid ratio16,and particle size less than106μm.More than96%of lead was effectively recovered in optimum condition.Based on analysis of variance,the reaction temperature,liquid/solid ratio,and NaCl concentration were determined as the most effective parameters on leaching process,respectively.Kinetics study revealed that chloride leaching of galena is a first-order reaction and the diffusion through solid reaction product and chemical reaction control the mechanism.The activation energy of chloride leaching of galena was determined using Arrhenius model as27.9kJ/mol.

Leaching optimization and dissolution behavior of alkaline anions in bauxite residue

Bauxite residue is a highly alkaline waste containing soluble alkaline anions, which can cause environmental concerns. The optimal leaching conditions, distribution of alkaline anions, types of pivotal alkaline anions and their dissolution behaviors were investigated based on the combination of single factors-orthogonal experiments and leaching stage experiment. Using a two-stage leaching, 86% of the soluble alkaline anions（CO3^2-, HCO4^-,Al（OH）4^-, OH^-） were leached with a L/S ratio of 2 mL/g, at 30 ℃, over 23 h. During the first stage of leaching, approximately 88% of alkaline anions were leached from the dissolution of free alkali（Na OH, carbonate, bicarbonate, NaAl（OH）4） with the rest originating from the dissolution of alkaline minerals（calcite, cancrinite and hydrogarnet）. Supernatant alkalinity was 69.78 mmol/L with CO3^2- accounting for 75%. Furthermore, carbonate leaching was controlled by solid film diffusion using the Stumm Model with an apparent activation energy of 10.24 kJ/mol.

Modeling and optimization of low-grade Mn bearing ore leaching using response surface methodology and central composite rotatable design

The application of leaching process to extracting Mn from a low-grade manganese ore was investigated using a software based design of experiments. Four main parameters, i.e. sulfuric acid concentration, oxalic acid concentration, time and temperature were considered in a central composite response surface design. The recoveries of Mn and Fe were selected as response of design. The optimum conditions under which the Mn and Fe recoveries were the highest and the time and temperature were the lowest were determined using statistical analysis and analysis of variance （ANOVA）. The results showed that Mn and Fe recoveries were 93.44% and 15.72% under the optimum condition, respectively. Also, sulfuric acid concentration was the most effective parameter affecting the process. The amounts of sulfuric and oxalic acid were obtained to be 7% and 42.50 g/L in optimum condition and the best time and temperature were 65 min and 63 ℃.

氢氧化钠焙烧法提取稀土电解渣中稀土的工艺研究

针对目前从氟盐体系稀土熔盐电解渣中回收稀土效率低的问题,提出了一种NaOH焙烧-盐酸优溶浸出法。系统考察了焙烧温度、焙烧时间、NaOH添加量,以及盐酸浓度、液固比、浸出温度、浸出时间对渣中稀土提取效果的影响。结果表明:在焙烧温度600℃、焙烧时间1.5h、NaOH与稀土熔盐电解渣质量比0.8∶1、盐酸浓度2mol/L、液固比8∶1、浸出温度40℃、浸出时间15min的工艺条件下,稀土浸出率为99.22%。

Soft Sensor for Ammonia Concentration at the Ammonia Converter Outlet Based on an Improved Group Search Optimization and BP Neural Network

The ammonia synthesis reactor is the core unit in the whole ammonia synthesis production. The ammonia concentration at the ammonia converter outlet is a significant process variable, which reflects directly the production efficiency. However, it is hard to be measured reliably online in real applications. In this paper, a soft sensor based on BP neural network (BPNN) is applied to estimate the ammonia concentration. A modified group search optimization with nearest neighborhood (GSO-NH) is proposed to optimize the weights and thresholds of BPNN. GSO-NH is integrated with BPNN to build a soft sensor model. Finally, the soft sensor model based on BPNN and GSO-NH (GSO-NH-NN) is used to infer the outlet ammonia concentration in a real-world application. Three other modeling methods are applied for comparison with GSO-NH-NN. The results show that the soft sensor based on GSO-NH-NN has a good prediction performance with high accuracy. Moreover, the GSO-NH-NN also provides good generalization ability to other modeling problems in ammonia synthesis production.

Optimization of selective leaching of Zn from electric arc furnace steelmaking dust using response surface methodology

The aim of this work is to investigate and optimize the effects of the leaching parameters on the selective leaching of zinc from electric arc furnace steelmaking dust （EAFD）. The response surface method was applied on the basis of a three-level Box–Behnken experimental design method for optimization of selective leaching parameters of zinc from EAFD. The leaching recoveries of zinc （YZn） and iron （YFe） were taken as the response variables, where the concentration of sulphuric acid （X1, mol/L）, leaching temperature （X2, °C）, leaching time （X3, min）, and liquid/solid ratio （X4, mL/g） were considered as the independent variables （factors）. The mathematical model was proposed. Statistical ANOVA analysis and confirmation tests were applied. A maximum of 79.09% of zinc was recovered while the minimum iron recovery was 4.08% under the optimum conditions of leaching time 56.42 min, H2SO4 concentration 2.35 mol/L, leaching temperature 25 °C and liquid/solid ratios. By using ANOVA, the most influential factors on leaching of zinc and iron were determined as H2SO4 concentration and leaching temperature, respectively. The proposed model equations using response surface methodology show good agreement with the experimental data, with correlation coefficients （R2） of 0.98 for zinc recovery and 0.97 for iron recovery.

Empirical model for bio-extraction of copper from low grade ore using response surface methodology

The copper extraction in shaking bioreactors was modeled and optimized using response surface methodology（RSM）. Influential parameters in the mesophilic bioleaching process of a low-grade copper ore including p H value, pulp density, and initial concentration of ferrous ions were comprehensively studied. The effect of leaching time on the response（copper extraction） at the 1st, 4th, 9th, 14 th and 22 nd days of treatment was modeled and examined. The central composite design methodology（CCD） was used as the design matrix to predict the optimal level of these parameters. Then, the model equation at the 22 nd day was optimized using the quadratic programming（QP） to maximize the total copper extraction within the studied experimental range. Under the optimal condition（initial p H value of 2.0, pulp density of 1.59%, and initial concentration of ferrous ions of 0 g/L）, the total copper extraction predicted by the model is 85.98% which is significantly close to that obtained from the experiment（84.57%）. The results show that RSM could be useful to predict the maximum copper extraction from a low-grade ore and investigate the effects of variables on the final response. Besides, a couple of statistically significant interactions are derived between p H value and pulp density as well as p H value and initial ferrous ion concentration which are precisely interpreted. However, there is no statistically significant interaction between the initial ferrous ion concentration and the pulp density. Additionally, the response at optimal levels of p H value and pulp density is found to be independent on the level of initial ferrous concentration.

Optimal design for buckets layout based on muck removal analysis of TBM cutterhead

The layout of the buckets for tunnel boring machine(TBM)directly affects the muck removal efficiency of cutterhead during excavation.In order to improve the muck removal performance for TBM,the optimal design of bucket layout was investigated.The whole muck transfer process was simulated by discrete-element method(DEM),including the muck falling,colliding,pilling up,shoveling and transferring into the hopper.The muck model was established based on size distribution analysis of muck samples from the water-supply tunnel project in Jilin Province,China.Then,the influence of the bucket number and the interval angle between buckets on muck removal performance was investigated.The results indicated that,as the number of buckets increased from four to eight,the removed muck increased by 29%and the residual volume decreased by 40.5%,and the process became steadier.Different interval angles between buckets were corresponding to different removed muck irregularly,but the residual muck number increased generally with the angles.The optimal layout of buckets for the cutterhead in this tunnel project was obtained based on the simulation results,and the muck removal performance of the TBM was verified by the actual data in the engineering construction.

Multi-objective optimization for leaching process using improved two-stage guide PSO algorithm

A mathematical mechanism model was proposed for the description and analysis of the heat-stirring-acid leaching process.The model is proved to be effective by experiment.Afterwards,the leaching problem was formulated as a constrained multi-objective optimization problem based on the mechanism model.A two-stage guide multi-objective particle swarm optimization(TSG-MOPSO) algorithm was proposed to solve this optimization problem,which can accelerate the convergence and guarantee the diversity of pareto-optimal front set as well.Computational experiment was conducted to compare the solution by the proposed algorithm with SIGMA-MOPSO by solving the model and with the manual solution in practice.The results indicate that the proposed algorithm shows better performance than SIGMA-MOPSO,and can improve the current manual solutions significantly.The improvements of production time and economic benefit compared with manual solutions are 10.5% and 7.3%,respectively.