水产类上市公司经营绩效评价及影响因素分析——基于DEA-Tobit模型

2012年以来水产类上市公司经营面临困局.该研究根据11家水产类上市公司2012～2014年的面板数据,首先运用DEA模型进行生产效率的评价,研究发现水产类上市公司的技术效率、纯技术效率和规模效率3年平均值都较高,但2014年整体绩效有走低的趋势;然后运用Tobit模型,分析经营绩效的影响因素,发现公司总资产周转率和高等教育人员比例与技术效率正相关,而研发人员比例与技术效率不相关.最后,从资产整合、加强营销、重视人才和发展休闲渔业等方面提出了提高水产类上市公司经营绩效的对策建议.     

Assessing the sustainability of cropping systems in single- and multi-site studies. A review of methods

The multiple new challenges facing agriculture require the development of innovative cropping systems with high environmental, economic and social performances. Many research programmes are currently focusing on the design of such cropping systems. Some include the multicriteria assessment of cropping systems by diverse methods and approaches. Some of these research programmes are supported by experimental or farmers’ networks, generating new opportunities for data analysis and raising new research and methodological questions. In this article, we provide an overview based on a review of 56 articles, comparing the various methods for sustainability assessment in single- and multi-site studies. Articles were classified according to three characteristics: (i) their objectives, (ii) the study design (single- vs. multi-site), (iii) the type of system assessed (fictitious vs. real). Our analysis was structured around four items: (i) the variables used to describe cropping systems and production situations and the use of these variables in the assessment process, (ii) the criteria and associated indicators assessed, (iii) the methods used to explore multiple aspects of the performance of cropping systems, (iv) the use of reference values. We identified key points to be taken into account in multi-site studies. The application of the proposed guidelines to experimental networks should facilitate the identification of high-performance cropping systems and the identification of the drivers of cropping system performance.     

Industry Perceptions of HERDA in Performance Horses

Hereditary equine regional derma asthenia (HERDA), an autosomal-recessive trait, found in Quarter Horses, causes abnormal collagen structure. Owing to current breeding practices, 3.5% of registered quarter horses and 28.3% of the cow horse population are heterozygote carriers. Research demonstrated homozygote horses develop hyperextensible skin susceptible to injury and other abnormal tissues containing high fibrillar collagen content. No research exists determining the effects of the disease in heterozygote carriers. Currently, 30% of cutting sires are HERDA carriers, potentially increasing the number of heterozygous individuals when bred. The objective of the present study is to gauge knowledge of the disease, perception, and concerns of the diseases’ impact on horse performance and perceived value and breeding decisions. A Qualtrics link was distributed to horse owners via extension specialists and was available online on equine-related Facebook pages. Overall group means and standard deviations for constructs were reported. A total of 228 responses were collected. Most participants were involved in reining and cutting and 34.6% reported they were very familiar with the disease. Participants (78.5%) reported that HERDA status affects value of a breeding animal. Owners of HERDA carriers (62.5%) noticed no difference in performance or injury compared with noncarriers. Respondents (95.2%) believed that all breeding animals should have HERDA status available. Respondents are attempting to make informed breeding decisions based on HERDA status by pairing carriers with noncarriers; however, it remains to be seen if that is adequate to control the disease. Education regarding breeding practices and its impact on the genetic pool are warranted.     

酸化剂、微生态制剂和寡糖对‘麒麟鸡’生长性能和消化道酶活力的影响

为了研究酸化剂、微生态制剂和寡糖单独和联合添加对‘麒麟鸡’生长性能和消化道酶活力的影响,选择健康1日龄‘麒麟鸡’192只,随机分成8个处理组,每个处理组3个重复,每个重复8只鸡,采用L8(23)完全正交试验设计进行试验,酸化剂水平为0、0.15%,微生态制剂水平为0、0.15%,寡糖水平为0、0.10%,试验期28天。结果表明:单独添加0.15%酸化剂可提高‘麒麟鸡’生长性能、消化酶活力;单独添加0.15%微生态制剂对‘麒麟鸡’生长性能无显著影响,可提高胃蛋白酶活力;单独添加0.10%寡糖可降低‘麒麟鸡’生长性能和胃蛋白酶活力;0.15%酸化剂、0.15%微生态制剂和0.10%寡糖2种或3种联合添加对提高‘麒麟鸡’生长性能和消化酶活力的互作效应不明显。     

电控喷油器流量性能检测试验装置

设计的电控喷油器性能测试装置,可有效检测喷油器的主要性能指标,为提高发动机燃油动力性、经济性以及降低排放提供了技术支持。检测试验证明,该测试装置具有效率快、精度高、性能稳定的特点,具有实际应用价值。     

小麦秸秆还田机粉碎装置性能影响因素试验与优化

利用设计的秸秆还田机粉碎装置进行了粉碎试验。以壳体包角、喂入速度、动定刀间隙为试验因素,秸秆的粉碎质量、粉碎功耗为试验指标,建立了粉碎质量和粉碎功耗的数学模型。随着喂入速度、壳体包角的增加和动定刀间隙的减小,粉碎功耗增大,粉碎质量提高。利用回归方程和主目标法,进行了参数的优化设计,结果为:粉碎室包角为70°、喂入速度为46.5m/s、动定刀间隙为10mm。     

横流式风机气动和噪声特性相似定律的研究

通过对两台几何相似但大小不同的横流式的试验，研究了该种风机的相似定律。证实了临界雷诺数的存在，超过该值后，气动和噪声特性的相似定律均成立，且临界值随风机尺寸的增大而增加，同时，风机尺寸以及叶轮与隔舌间的间隙对风机的相似定律也有影响。     

地轮驱动离心式化肥撒布机的设计与试验

设计了一种由地轮驱动的离心式化肥撒布机，对其撒肥性能进行了试验，测定了撒肥量、撒肥幅宽、撒肥形状、撒肥均匀性，并进行了搭接撒施的均匀撒肥试验，该机与人工撒肥进行了比较。结果表明，这种新型的地轮驱动离心式化肥撒布机完全能满足使用要求。     

微型自吸施涡管道泵的研制

针对市场要求，构思了一种新型结构的旋涡管道泵。文章了阐述其工作原理、自吸机理及水力设计方法，通过对样机20GL1.5-10-0.25试验结果进行分析，验证了该泵的设计方面的可取性和独到性。