Spatial Autocorrelation Panel Regression: Agricultural Production and Transport Connectivity

Transport infrastructure is an important determinant of agricultural productivity. Using various new spatial data, the paper measures different types of transport accessibility and estimates their impacts in Ethiopia. The paper takes advantage of a historical event that Ethiopia, a landlocked country, ceased freight rail operations connecting its capital and the main seaport in the late 2000s. Using the substantial changes in transport accessibility, the spatial autocorrelation panel regression is applied to show that the proximity to close markets and the access to the port are of particular importance for agricultural production. The elasticity is estimated at about ?0.05 to ?0.13, depending on type of accessibility. It is also found that there are considerable spillover effects that come from the spatial autocorrelation errors, meaning that crop production at one place is affected by its neighborhood environment, possibly including land fertility and weather conditions.

     

石雕刻制品加工设备数控系统断点信息保存的方法

本文以山东省石材工程技术研究中心开发的新型数控石材雕刻制品加工设备为研究背景,根据石材雕刻制品加工的特点,分析了加工过程中常出现的故障及产生的原因和后果,优化配置了加工断点需要保存的信息,设计了基于Windows平台数控系统的实现断点信息保存、读取的程序。实践证明,数控系统中的断点保存功能缩短了故障处理时间,有效地保证了石材制品的加工效率。     

强实时系统静态优先级调度的可调度性分析

文章在系统阐述和借鉴经典的强实时系统静态优先级调度理论的基础上,通过引入忙周期的概念,分析了任务时限超过任务周期的实时系统任务集的可调度特性,拓宽了该理论的应用范围,更有利于实时系统的设计者对任务的运行时间行为进行事前分析与预测。     

浅谈基建矿井大型机电设备安装调试与管理

对如何抓好基建矿井的大型机电设备安装调试与管理工作提出了建设性的意见。     

我国珠宝行业发展现状与展望

概述我国珠宝行业发展历程,分析我国珠宝行业发展的有利条件,并指出珠宝行业的发展趋势。目前,我国珠宝的市场需求不断增强,珠宝加工水平不断提高,珠宝产业集群效应突显,珠宝资源的综合开发能力进一步加强。未来珠宝企业将以三线城市为开发重点,增加自营零售点,拓宽加盟渠道,建立网上销售渠道,加强品牌建设,提高设计能力,以差异化赢得市场。     

高产辅酶Q10类球红细菌的化学诱变筛选及其发酵培养基优化

利用菌株对（维生素K3+叠氮化钠+对羟基苯甲酸）的复合抗性作为筛选标记,对产辅酶Q10的类球红细菌（Rhodobacter sphaeroides）使用亚硝基胍进行化学诱变,筛选高产菌株并采用响应面法优化其发酵培养基。结果表明,经诱变选育得到一株遗传稳定的辅酶Q10高产菌株R.sp3-7,其最佳发酵培养基组成为：葡萄糖31.7 g/L,玉米浆干粉5.6 g/L,（NH4）2SO4 5.3 g/L、谷氨酸钠 3.0 g/L、NaCl 3.0 g/L、MgSO4·7H2O 12.5 g/L、KH2PO4 3.0 g/L、CaCO3 2.0 g/L、辅液1 mL/L。在此培养条件下,诱变菌株R.sp3-7的辅酶Q10产量达（93.63±0.59） mg/L,与出发菌株相比提高了116.8%。 关键词：中图分类号：TS201.3 文章编号：0254-5071（20１6）06-0090-06 doi:     

Development of a hybrid method to improve the sensitivity and uncertainty analysis for homogenized few-group cross sections

In the framework of two-step method of reactor core calculation, few-group homogenized cross sections generated by lattice-physics calculations are key input parameters for the three-dimensional full-core calculation. Conventional method for few-group cross-sections sensitivity and uncertainty (S&U) analysis related to the nuclear data was performed based on the effective self-shielding cross sections instead of the continuous-energy cross sections, which means resonance self-shielding effect (implicit effect) is neglected. Furthermore, the multi-group covariance data is generated from the continuous-energy cross sections. Therefore, in order to perform S&U analysis with respect to the continuous-energy cross sections for both accuracy and consistency, a hybrid method is proposed in this paper. The subgroup-parameter sensitivity-coefficients are calculated based on the direct perturbation (DP) method. The sensitivity-coefficients of the effective self-shielding cross sections and the responses (k_eff and few-group homogenized cross sections) are calculated based on the generalized perturbation theory (GPT). A boiling water reactor (BWR) pin-cell problem under different power conditions is calculated and analyzed. The numerical results reveal that the proposed hybrid method improves the sensitivity-coefficients of eigenvalue and few-group homogenized cross sections. The temperature effects on the sensitivity-coefficients are demonstrated and the uncertainties are analyzed.     

桩靴在静载荷作用下的沉降预测

为了研究桩靴在静载荷作用下的沉降,基于圆孔扩张理论,推导出桩靴在荷载作用下的桩端阻力表达式.将桩端阻力作为桩靴受压状态下的荷载传递函数,结合桩侧摩阻力函数,采用分段位移迭代算法进行计算,预测出桩靴在受压状态下的荷载—沉降曲线.开展砂土中的桩靴静载模型试验,将模型试验结果与理论结果进行对比验证.结果表明:推导的理论公式计...     

Core design study on CANDU-SCWR with 3D neutronics/thermal-hydraulics coupling

Using separated heavy water as moderator and supercritical water (SCW) as coolant introduces challenge for CANDU-SCWR to get a negative coolant void reactivity (CVR), due to which the moderator thickness of the fuel channel is optimized in this paper. When SCW flows through the core, there is a rapid variation in SCW density, which is directly related to the neutron spectrum and subsequently to the power distribution, so the 3D core neutronics/thermal-hydraulics coupling is needed to accurately evaluate the core coolant density and power distribution. In this paper, the neutronics calculation is computed with 3D fine mesh diffusion code while the thermal-hydraulic calculation is based on single channel model, they are coupled with each other automatically by a link code. Further, the in-core fuel management can be simulated by the link code to search the equilibrium cycle. Based on these calculation models, a CANDU-SCWR equilibrium core is designed with a thermal power of 2540 MW, the core equivalent diameter is 4.30 m and the active length is 5.94 m. A 3-batch fuel management scheme with a cycle length of 350 EFPD is used. The numerical results show that a high average outlet coolant temperature of 625 °C is achieved with a maximum cladding surface temperature less than 850 °C. The maximum linear heat generation rate is 50.6 kW/m, the average discharged burnup is 38.1 GWd/tU, and the CVR is negative throughout the cycle.     

色彩设计与选择

在视觉设计中,色彩选择的基本动机之一是为了吸引注意力。高能见度的原色可获得最佳的注意力,而在一定时期内,其深浅变化则应根据流行趋势等一些色彩属性形成色彩系列以增加特殊的感情吸引力,当确定了色彩基本规格之后,将这些色相组成统一的设计作品,就要遵循色彩组合形式法则。功能色彩、市场色彩以及构成色彩这三个方面均不可偏颇。