The impact of conservation tillage on maize yield and input demand: the case of smallholder farmers in north‐west Ethiopia

This study analyses the economics of conservation tillage (CT) with respect to its effect on maize yield and chemical fertiliser, herbicide, and female and male labour demand. We estimate production and input demand functions using seemingly unrelated regressions on plot‐level cross‐sectional farm household data collected in the north‐west of Ethiopia. A two‐step control function is applied to address potential endogeneity bias due to the inclusion of the CT adoption decision as an explanatory variable. Our results show that CT increases maize yield and chemical fertiliser demand. Additionally, the results show that the adoption of CT reduces female and male labour required for crop production. However, this is achieved through the increased use of herbicides, which might have an undesirable health and environmental effects.     

China feels the heat: negative impacts of high temperatures on China's rice sector

We analysed a county‐level data set of single‐season rice yield and daily weather outcomes in China to examine the effects of temperature on China's rice sector. We found that rice yield exhibited highly nonlinear responses to temperature changes: rice yield increased with temperature up to 28°C and decreased sharply with higher temperatures. Holding current growing seasons and regions constant, average rice yield in China is projected to decrease by 10–19 per cent by 2050 and 11–33 per cent by 2070 due to future warming under the global climate models HadGEM2‐ES and NorESM1‐M. These results imply that future warming poses a major challenge for Chinese rice farmers and that the effectiveness of adaptations will depend on how well they reduce the negative temperature impacts on rice yield because of very hot days.     

刍议中国劳动力价格与经济增长路径转变

改革开放以来,中国经济取得了令世人瞩目的成就,与此同时,经济运行中不和谐的因素也日益增加.投资和消费的比例关系失衡,表现为投资率偏高而消费率偏低.从劳动者收入入手研究投资、消费比例问题,在研究中国劳动力价格的现状后得出结论:相对于居民生活密切相关的粮价、油价、水电费、通讯费、教育费、医疗费来说,中国劳动力价格太低,因此,提高劳动力价格,增加其收入才是破解投资消费失衡的"密钥",也是促进中国经济从依赖投资的增长方式向依靠消费拉动经济增长方式的增长路径转变的"治本之道".     

污水处理厂的脱氮除磷改造

结合城镇污水处理厂脱氮除磷改造工程实例，对老氧化沟进行功能区划分、设备改造：增加好氧区溶解氧浓度，降低缺（厌）区溶解氧浓度；同时适当增容，延长氧化沟水力停留时间和污泥泥龄。运行结果表明，系统出水主要指标稳定达到GB18918—2002一级A标准。     

“三提一降”管理模式在井下作业系统的实践

在井下作业系统实施的“三提一降”管理新模式，通过实施“提升素质、提高质量、提高效率、降低成本”4项措施，把握精细化、系统化、集约化、一体化管理内涵，取得了队伍结构初步优化、施工效率明显提升、工程质量得到保证、增收节支效果突出等良好管理效果，是促进井下作业系统解困扭亏、解决深层次矛盾、保障油田增储稳产、理顺内部管理流程的重要途径，不仅提升了系统的管理水平，同时，也有力保障了油田千万吨生产任务的完成。     

广西容县浪水电站挖潜改造展望

广西容县浪水电站是一座以发电为主的多功能电站,在县电网和梯级开发中处于骨干和中心地位。近年来,随着工农业的迅猛发展和社会的需求,当地的用电量迅速增长,因此浪水电站需要进一步挖潜改造和扩容增效,以确保其在县电网中的地位和作用。     

石化产品的结构优化模型

石化产品及主要原料－原油的价格变化速度较快，这就要求企业根据市场变化及时进行产品结构调整。结合一个具有代表性的石化企业实际，运用优化方法，以原油加工量、产品收率为主要指标进行石化产品结构优化，为企业生产决策提供可靠的依据。     

证券市场成交量对收益率波动性影响的实证分析

本文根据上海证券市场上证综合指数2005年1月1日到2006年1月1日的复合收益率和日成交量。用GARCC模型描述日成交量对复合收益率的波动性影响。在GARCH模型中加入当期交易量、滞后一期的交易量，结果表明当期交易量变化率能明显削弱收益率条件方差的波动性，而滞后一期的成交量只通过对当期的成交量间接的影响复合收益率。     

中国经济的发展阶段研究

经济发展是指随着经济增长而出现的经济、社会和政治结构的变化。本文将经济发展研究分成收入、城市化、产业、消费和科技五个方面,运用多种参数指标,立足世界经济的未来与过去,得出我国经济发展的阶段、特点和规律。作者根据国内外关于一国经济发展阶段和中国发展阶段的现实,选择工业化和城市化作为核心指标,对比美国经济发展历程,得出我国经济发展处于“工业化和城市化‘双中期’区间”的判断;并在此基础上分析了“‘双中期’区间”最新时点的关键特征;概括出我国经济发展的双重性规律,提出了中国经济发展战略思路及政策建议。     

Constant per capita consumption paths with exhaustible resources and decaying produced capital

We introduce decay in produced capital and exogenous technical progress to the recent “Solow Model” of Asheim et al. with population growth and observe the possible collapse of the economy given too high a rate of decay. “Enough” technical progress can restore sustainable per capita consumption.