Agricultural Policy, Climate Factors and Grain Output: Evidence From Household Survey Data in Rural China

This paper estimates a stochastic frontier function using a panel data set that includes 4 961 farmer households for the period of 2005-2009 to decompose the growth of grain production and the total factor productivity （TFP） growth at the farmer level. The empirical results show that the major contributor to the grain output growth for farmers is input growth and that its average contribution accounts for 60.92% of farmer’s grain production growth in the period of 2006-2009, whereas the average contributions sourced from TFP growth and residuals are only 17.30 and 21.78%, respectively. The growth of intermediate inputs is a top contributor with an average contribution of 44.46%, followed by the planted area （18.16%）, investment in fixed assets （1.05%）, and labor input （-2.75%）, indicating that the contribution from the farmer’s input growth is mainly due to the growth of intermediate inputs and that the decline in labor inputs has become an obstacle for farmers in seeking grain output growth. Among the elements consisting of TFP growth, the contribution of technical progress is the largest （32.04%）, followed by grain subsidies （8.55%）, the average monthly temperature （4.26%）, the average monthly precipitation （-0.88%）, the adjusted scale effect （-5.66%）, and growth in technical efficiency （-21.01%）. In general, the contribution of climate factors and agricultural policy factor are positive and significant.

Weight Determining of Factors Influencing Grain Output Based on Entropy Weight Method

This article selects 8 main factors(the number of rural employees,total power of agricultural machinery,effective irrigation area of crops,growing area of grain crops,fertilizer consumption,electricity consumption in rural areas,area affected and area covered) as the factors influencing grain output,and offers the method of determining weight of factors influencing grain output using entropy weight method.According to the relevant data in the period 1985-2005,we analyze the weight of factors influencing grain output in China by example.The results show that the electricity consumption in rural areas has the greatest impact on grain output,followed by total power of agricultural machinery,fertilizer consumption and area covered.To increase grain output,we must enhance the degree of mechanization,free people from the former process of direct cultivation,strengthen water conservancy construction,and do a good job in disaster prevention and mitigation.

Measurement and Comparison of Output Factors Using Two Detectors for NOVAC7 IntraOperative Radiotherapy Accelerator

The aim of this work was to evaluate and compare the performance of comparatively new synthetic PTW 60019 microDiamond with PTW 60017 Diode E detector in measuring the output factors (OF) of IntraOperative Radiation Therapy (IORT) electron beams. For a given electron beam, OFs are defined as the ratio of the dose for any applicator size at the depth of maximum to that for a reference applicator. IORT is an innovative treatment technique that delivers a large single fraction of radiation dose to the tumor bed during surgery. The electron beams considered in this study were generated by the mobile NOVAC7 system. This device produces high-dose-per-pulse electron beams with four different energies in the range from 3 MeV to 9 MeV. We performed measurements for two higher energies, namely 7MeV and 9 MeV. The beam collimation was performed through Perspex (PMMA) cylindrical applicators with different diameters. The accurate dose delivery of IORT tightly depends on the precision of measured dose by reference applicator and the output factors of clinical applicators. The output factors were measured using microDiamond and Diode E detectors. The microDiamond detector performance was compared with a Diode E detector. Determined output factors of two detectors were in good agreement. The maximum deviations of output factors for microDiamond were found 2.74%, and 2.17% for 7 MeV and 9 MeV, respectively with respect to the PTW Diode E. The microDiamond detector was shown to exhibit excellent properties for output factor measurements and could be considered as a suitable tool for electron beam dosimetry.

Measurement and Analysis of PDDs Profile and Output Factors for Small Field Sizes by cc13 and Micro-Chamber cc01

Small radiation fields are abundantly used in modern radiotherapy techniques like in IMRT and SRS. In order to commission these techniques, dosimetric data for small fields is required. The purpose of this study is to compare dosimetric measurements with two different ion chambers cc13, and cc01 for smaller fields. Dosimetric measurements are beam profile, output factor, pdds, and collimator factor. Dosimetric data is acquired in water phantom for two different photon beam energies 6 MV and 15 MV with zero gantry angle. In beam profiles cc13 chamber, measure wider penumbra as compare to cc01. And this wider measurement of penumbra occurs for smaller as well as for larger field sizes. Accumulated relative error in the measurement of penumbra for number of field sizes and 6 MV at dmax, and at 10 cm depth are 34.32% and 27.72% respectively. Accumulated relative error in the measurement of penumbra for number of field sizes and 15 MV at dmax, and at 10 cm depth are 28.49% and 23.92%. In case of output factor for smaller fields cc13 underestimates the output factor relative to cc01, with non-linear increase for smaller fields. But for larger fields, this increase in output factor is almost linear difference of two chambers is decreased. For very smaller fields × 2 cm, relative error in output factor of cc13 and cc01 is greater than 5% and rapidly increases with decreasing field size. But for lager fields, this relative error is negligible. In measurement of pdds after the buildup region difference occurs in the response of two chambers cc13 and cc01 for smaller fields. For field sizes ≤2 cm × 2 cm average cc13-cc01 at various depths 30 cm, 40 cm, 50 cm, 60 cm, 70 cm, and 80 cm is almost greater than 0.5 cm. And similarly as output factor, this difference (cc13-cc01) increases with field size decreasing.

The Impact of Small Field’s Off-Set on Output Factor in Intensity Modulated Radiation Treatment

In intensity modulated radiation treatment (IMRT) planning, the use of asymmetrically collimated fields that are placed on central axis or its off-set is mostly required. Output is the main topic discussed today for extremely small and/or severe irregularly shaped fields. The air scatter data are involved directly or indirectly in obtaining the output. Despite the fact that extensive data have been published in many studies to provide a guide on the magnitude of output factor for clinical accelerators, there are very few data reviewed about output factor in-air or phantom for off-set fields. This study was aimed to investigate the impact of these conditions for small fields. This study was conducted in Elekta Synergy linear accelerator which produces 6 MV X-ray energy. The in-air output factor (Sc) has been measured by CC04 ion chamber with brass-alloy “build-up” cap and Dose-1 electrometer, and the total output (Scp) measurements were carried on at dose maximum depth in phantom by the same chamber and Thermoluminescence dosimeter (TLD) for 1 - 10 cm2 fields. The all measurements at center of isocenter and off-set fields at three directions (X2, Y1, Diagonal) were done. By decreasing field size from 10 to 2 cm2 at isocenter, the Sc value using CC04 was decreased to 5.4% and Scp using CC04 and TLD to 14.5% and 11% respectively. By increasing off-set value, the Sc and Scp values were increased in all directions comparing to central fields. The maximum increase was obtained in Y1 direction for Sc and Scp. TLD results for Scp is slightly higher than CC04. The dosimetric properties of small fields and their off-set should be evaluated and modelled appropriately in the treatment planning system to ensure accurate dose calculation in Intensity Modulated Radiation Treatment.

农户种植饲草料投入产出及种植行为影响因素研究——以内蒙古巴彦淖尔市杭锦后旗和磴口县为例

国内消费结构及农业结构调整背景下,中国畜牧业迅速发展,饲草料需求不断增加,但是国内饲草料供应不足、安全问题凸显。在“粮改饲”试点旗县进行实地调研,了解当地农户饲草料种植的投入产出情况,利用Logit、2SLS及LIML模型对农户种植饲草料行为的影响因素进行实证研究。结果显示,调查区域农户种植的饲草料主要以青贮玉米、苜蓿及燕麦草为主,种植苜蓿草的经济效益比其他饲草料高,2021年苜蓿草纯收益可达22 005元/hm^(2),比青贮玉米和燕麦草分别高出4 590元/hm^(2)元和12 180元/hm^(2),但是农户种植饲草料尤其苜蓿草的积极性并不高。探究农户选择种植饲草料行为的影响因素,发现政策激励、土地禀赋及组织制度因素对农户饲草料种植行为有显著的正向影响,提出政府应该尽快建立完善的土地流转市场体系,助力农户扩大种植规模,顺利进行种植业结构调整,加大饲草料种植面积,促进为养而种的良性循环,解决养殖业饲草料短缺问题以及鼓励各类合作社发挥合作制度优势,帮助农户降低种植饲草料的投入成本,拓宽饲草料的销售渠道,增加农民收入的对策建议。

疫情后深圳市生活垃圾产生量的预测及变化分析

疫情后针对生活垃圾产生量的变化,开展预测并对结果进行分析,是地方政府科学制定相关规划、合理布局环卫设施建设的重要依据。因此,立足深圳市疫情前后数据,结合灰色关联度模型、多元线性回归等方法,分析2022—2035年生活垃圾产生量预测值的变化。结果表明,生活垃圾产生量保持逐年增长趋势,规划期末水平年(2035年)的具体数值有一定程度调整。预测到2035年的生活垃圾产生量为45 547 t/d,其中再生资源回收量为14 576 t/d,生活垃圾处理处置量为30 971 t/d。建议各项环卫设施建设可灵活调整设施规模及建设周期,提升城市垃圾处理效能。

“双碳”目标下黄河流域旅游绿色生产率时空分异特征及影响因素——以陕西段为例

陕西作为黄河流域旅游资源赋存高密度区,其绿色发展对黄河流域高标准高质量地实现“双碳”目标起着重要作用。收集2010—2021年相关数据,采用非期望产出的SBM模型、ML指数及Tobit回归模型等方法对陕西旅游绿色生产率(TGTFP)的时空分异特征及影响因素进行了分析。研究表明:(1)在时序发展上,2010—2021年内陕西旅游能源消耗与碳排放总量呈上升态势,其静态TGTFP唯有2017年实现有效,动态ML指数在2010—2013年和2014—2019年内实现有效,但其他年份均表现为无效,在发展过程中均呈左高右低的山峰型。(2)在空间分异上,TGTFP呈现“关中最强,陕北高于陕南”的分异特征,三大区域内部市域发展渐趋均衡,而三大区域间分化显著导致了陕西总差异扩大。(3)影响因素上,政府干预、环境规制及城镇化水平等外部因素对陕西旅游绿色生产率具有显著的推动作用,但仍有强烈的内部阻力来自旅游总收入、旅游能源消费及碳排放。

数字化转型对企业全要素生产率的影响——基于产业链关联视角

文章选取上市公司年报以及投入产出表的相关数据,通过面板数据模型考察数字化转型对企业全要素生产率的影响效应及其作用机制。结果表明:数字化转型能够提升企业全要素生产率,并且在缓解内生性问题和进行一系列稳健性检验后结论依然成立;数字化转型能够通过前向关联、后向关联两种渠道来增强产业链关联的创新效应和结构效应,进而促进企业全要素生产率增长;数字化转型对企业全要素生产率增长的促进作用存在行业异质性,在劳动密集型和竞争性行业的作用效果更为明显。

产业数字化如何走“实”向“深”?——数字要素全产业链溢出的内在逻辑与测算实践

随着数字技术的持续更新迭代,数字服务逐步推进生产管理模式向平台化、系统化变革,促使产业数字化向“技术+服务”融合赋能的模式演变。本文将产业数字化解构为数字要素的产业间价值溢出过程,运用投入产出技术定量测算数字要素溢出程度及驱动因素,从而基于技术、服务双维度探究数字要素赋能产业升级的内在机制,为推动现代化产业体系建设提供理论参考。研究发现,数字技术通过替代并协同传统技术推进产业升级,而数字服务通过优化中间环节进入再生产过程,实现跨部门的协同共享与资源整合,延长并创新产业链条,提升全产业链经济效率。目前国民经济各主要部门基本转向服务主导的数字化转型阶段,产业间价值联动能力显著增强,全产业数字化增量转型的链式特征逐步显现。同时,数字技术溢出受数字创新效应驱动并通过产业自主数字创新延续,数字服务溢出受需求拉动效应影响,产业间流转缓慢,产业数字化内生动力仍待开发。

年龄影响科研产出吗?——基于高校图书馆员科研论文产出的分析

高校图书馆不断增强学术性的需求与馆员科研积极性不高、产出低的鸿沟在持续加深,探讨高校图书馆员高峰科研论文产出年龄和变化趋势,对建立全职业生涯科研激励机制、提升馆员的专业性和图书馆的学术水平有积极意义。以高校图书馆员2011—2022年在图情类12种CSSCI期刊的发文和553名高校图书馆员高产作者为研究对象,统计发现:高校图书馆员的科研论文产出呈现单峰模式,青年时期是高产期,之后随年龄增长产出减少,高峰年龄有逐步后移的趋势;高校图书馆女性馆员的发文高峰年龄区间和科研持续性要短于高校图书馆男性馆员,不同层次的高校图书馆员在科研生命周期上基本无差异。在分析高校图书馆员科研论文产出差异的基础上,提出了珍惜黄金科研期、为青年馆员创造科研条件、优质资源向女性馆员倾斜、重视不同年龄阶段馆员科研诉求等提升高校图书馆员科研产出的措施。

中国战略性新兴产业投入产出表编制及部门结构分析

编制2020年战略性新兴产业投入产出表对深入考察战略性新兴产业现状、合理配置行业资源、调整产业结构具有深远意义。编制过程中的主要难点在于分离系数的确定,为此文章创新性地将时间比例因子漂移法与传统就业人数法相结合,有效提升了数据的科学性,为常常受制于数据可获得性的分离系数提供了有效参考。基于时间比例因子漂移法的编制结果表明,战略性新兴产业部门大多存在乘数效应和溢出效应强的现象,相较而言,反馈效应占比则处于弱势;战略性新兴产业需求对劳动者报酬的拉动主要是由技术更新换代较快的产业,如新一代信息技术产业所引发;进一步地,由网络密度、凝聚子群、网络出入度从供需视角观测战略性新兴产业部门间经济技术联系程度并分辨产业链中的上下游部门。

密度峰值聚类在塔机损伤诊断中的应用研究

建立塔机有限元模型,获取塔机完好状态和各损伤工况的各采集点的动态位移。提出了两种模型建立方法,基于悬臂梁的双输入单输出模型和基于时域数据的动态双输入单输出模型,对基于时域数据的双输入单输出模型首先利用最小二乘法计算参数初值,进一步利用粒子群优化方法进行参数优化,提高了模型精度。以完好工况的塔机数据为基础,建立基于悬臂梁的双输入单输出模型和基于时域数据的双输入单输出模型,计算参数,建立损伤识别模型,用待检状态的位移数值拟合模型,用两种模型计算出的残差方差做损伤因子,利用密度峰值聚类方法对损伤因子进行分析,实现了对塔机的损伤判定和损伤位置的确定。这种基于密度峰值聚类的诊断方法可对塔机微小损伤进行智能诊断和位置确定,该方法只需要塔机完好状态的数据和待检状态的数据即可自动诊断,解决了塔机损伤识别中损伤数据难以获取,因而无法实现智能训练和诊断的问题。

基于FCM-LSTM的光热发电出力短期预测

对光热电站的出力进行短期预测,可以有效应对太阳能随机性和波动性带来的影响,为电网调度做好准备.该文以青海某光热电站为例,首先使用模糊C均值聚类算法对预处理后的实验数据进行分类,然后通过分析不同聚类类型下出力和气象数据中各因子间的关联程度,充分挖掘出数据间的关系,确定不同类型预测模型的输入变量,进而构建出不同类别下的长短期记忆神经网络预测模型.结果表明,与传统长短期记忆神经网络模型、BP神经网络模型、支持向量机模型和随机森林模型的预测结果相比,基于模糊C均值聚类的长短期记忆神经网络预测模型效果良好,大幅减少了预测误差,验证了该预测模型的有效性.

我国行业间尾部风险溢出的测度及时空驱动因素研究

基于经济金融的共生共荣关系,本文采用LASSO分位数回归构建我国金融与实体行业间的尾部风险网络,利用复杂网络分析法对行业间尾部风险溢出进行测度分析,并从时空两个维度探讨行业尾部风险溢出的驱动因素。研究结果显示,第一,我国经济金融系统中的31个行业形成了“牵一发而动全身”的尾部关联网络,金融行业间、实体行业间以及金融与实体行业之间均存在密切的尾部关联,而且在与实体行业的互动中,金融行业内部存在结构性不平衡。第二,经济金融系统中的风险传染源既可能来自金融行业,也有可能来自实体行业,银行、医药生物、计算机和建筑装饰是经济金融系统中重要的“风险驱动者”。第三,在空间维度上,行业间投入产出关联越密切,其尾部风险溢出水平越高,且相比前向关联,后向关联对行业间尾部风险溢出的解释力更强,即尾部风险主要沿产业链从下游向上游行业进行逆向传导;两两行业间的收益相关性和波动相关性越高,尾部风险溢出越强;行业自身风险水平越高,其接收其他行业的尾部风险溢出越强。在时间维度上,宏观经济环境和融资环境是行业尾部风险溢出动态变化的主要驱动因素。

重油催化裂解在炼化企业布局影响因素研究

随着我国炼化产业的快速发展,原油一次能力已接近10×10^(8)t/a,但汽柴油消费总量受经济结构转型、新能源替代等因素影响,汽油需求量即将达峰,柴油需求量已呈现下降趋势。与之相对应的,乙烯、丙烯的下游化工产品未来仍有一定增长空间。重油催化裂解装置相较常规催化裂化可大幅减少汽柴油产量、增产化工原料,已成为炼化企业实现“减油增化”转型升级的重要路径之一。在具体项目布局规划时,由于炼化企业装置结构、所处地域市场条件等情况不同,分析企业是否适宜布局该装置是决策者的主要难点。结合催化裂解技术特点,总结分析了“企业所在地油品过剩程度、减油增化程度、化工品目标市场、资源利用程度、苯资源平衡、催化裂解原料性质、存量资产利用程度、投资回报率”共八项影响重油催化裂解项目决策实施的主要因素,为投资决策者提供支持依据。

改进反激拓扑模式下远端稳压电源控制方案

为提高远端稳压电源的供电质量,最大限度的在高可靠性前提下保证发射设备输出电压快速、平稳地达到设定值,提出一种改进反激拓扑模式下远端稳压电源设计方式,并建立相应数学模型。设计了前置论域整定的模糊比例积分微分(PID)控制算法,通过论域整定模型将模糊PID参数直接映射到模糊规则下,消除试凑法偶然性的同时消除了量化因子对误差的放大作用,有效地避免了过度调整的现象;引用模糊逻辑来实时处理远端稳压电源的动态参量值,并根据反模糊映射函数将生成的量化值映射到控制元件。仿真环境模拟结果表明:与模糊PID控制相比,前置论域整定的模糊PID控制算法具有优良稳态性能,调节时间缩短48.1%,响应时间缩短了28.6%并降低到1.4 ms;与此同时,该控制方案能够有效地抵抗突发性干扰,稳压输出时间缩短了45.5%,响应时间缩短到37.5%。实验结果表明:前置整定模糊PID控制算法可以运用到实际工业环境中,与工业环境下传统控制算法比,前置整定模糊PID控制算法可以大幅提高远端稳压电源的供电质量,具备优良的鲁棒性。

磁致伸缩执行器数学建模与仿真分析

针对设计的磁致伸缩执行器的输出特性及其内部复杂物理现象,基于电磁学理论、Jiles-Atherton模型、能量守恒理论、结构动力学理论提出了更为准确的执行器动力学行为描述模型并分析。上述模型考虑输入电流、磁导率、动态损耗、电磁力等多种因素间的关系及其对输出特性的影响,以Jiles-Atherton模型定义磁致伸缩材料并通过maxwell软件对以磁致伸缩材料为核心的执行器进行有限元仿真分析,将仿真结果与数学解析模型结合并加以修正,得到更加准确的系统动力学模型。最终在MATLAB/Simulink中搭建系统动力学模型仿真分析发现,由电磁场所产生的交变电磁力导致磁致伸缩棒预压力偏置现象对执行器输出性能较大,而电流、动态损耗及磁导率通过影响磁场进而影响执行器输出。

新型科研机构创新绩效驱动因素的动态仿真研究

基于系统动力学方法厘清新型科研机构创新过程中要素间的耦合作用与反馈关系,映射出人才集聚、技术创新和成果转化三个子系统,构建新型科研机构创新系统动力学模型。以2018—2021年江苏南京市的新型科研机构为样本,通过Vensim软件仿真分析新型科研机构创新绩效驱动因素的变动影响效应及演化规律。研究发现,研发资金投入、研发人员质量和科研自主权对新型科研机构科技成果产出的促进作用更显著,人才收益分配对新型科研机构创新总收益的促进作用更显著,网络关系水平和市场需求匹配系数对新型科研机构的科技成果产出与创新总收益均有促进作用。最后,从研发资金投入、人才团队建设、激励机制、对外合作交流和市场机制等方面为科学推进新型科研机构的良好运行与高质量发展提出建议。

碳排放权交易提高了城市全要素碳排放效率吗?——基于内生方向距离函数模型的研究

减碳措施一般会带来总产出的降低,因此有必要从全要素效率的角度评估减碳政策。本文构建了一个方向距离函数模型,允许各决策单元有不等的减排因子,扩大了生产可行集的范围,同时采用了内生的方向向量,避免在选择方向向量时过于主观。基于这一模型本文重新测算了城市层面全要素碳排放效率,并实证分析碳交易政策对其的影响,研究发现,试点政策能够提高城市全要素碳排放效率;中介效应表明,试点政策会通过产业结构和绿色创新等途径提高城市碳排放效率;异质性分析发现,试点政策对于高行政等级和人口规模较大城市的碳排放效率影响更明显。因此,应扩大政策试点范围、鼓励产业结构优化、推广绿色技术创新、制定因地制宜的试点政策等进一步提升碳排放权交易制度的绿色发展效应。