Invited review: Large-scale indirect measurements for enteric methane emissions in dairy cattle: A review of proxies and their potential for use in management and breeding decisions

Efforts to reduce the carbon footprint of milk production through selection and management of low-emitting cows require accurate and large-scale measurements of methane (CH₄) emissions from individual cows. Several techniques have been developed to measure CH₄ in a research setting but most are not suitable for large-scale recording on farm. Several groups have explored proxies (i.e., indicators or indirect traits) for CH₄; ideally these should be accurate, inexpensive, and amenable to being recorded individually on a large scale. This review (1) systematically describes the biological basis of current potential CH₄ proxies for dairy cattle; (2) assesses the accuracy and predictive power of single proxies and determines the added value of combining proxies; (3) provides a critical evaluation of the relative merit of the main proxies in terms of their simplicity, cost, accuracy, invasiveness, and throughput; and (4) discusses their suitability as selection traits. The proxies range from simple and low-cost measurements such as body weight and high-throughput milk mid-infrared spectroscopy (MIR) to more challenging measures such as rumen morphology, rumen metabolites, or microbiome profiling. Proxies based on rumen samples are generally poor to moderately accurate predictors of CH₄, and are costly and difficult to measure routinely on-farm. Proxies related to body weight or milk yield and composition, on the other hand, are relatively simple, inexpensive, and high throughput, and are easier to implement in practice. In particular, milk MIR, along with covariates such as lactation stage, are a promising option for prediction of CH₄ emission in dairy cows. No single proxy was found to accurately predict CH₄, and combinations of 2 or more proxies are likely to be a better solution. Combining proxies can increase the accuracy of predictions by 15 to 35%, mainly because different proxies describe independent sources of variation in CH₄ and one proxy can correct for shortcomings in the other(s). The most important applications of CH₄ proxies are in dairy cattle management and breeding for lower environmental impact. When breeding for traits of lower environmental impact, single or multiple proxies can be used as indirect criteria for the breeding objective, but care should be taken to avoid unfavorable correlated responses. Finally, although combinations of proxies appear to provide the most accurate estimates of CH₄, the greatest limitation today is the lack of robustness in their general applicability. Future efforts should therefore be directed toward developing combinations of proxies that are robust and applicable across diverse production systems and environments.     

Extending RSA cryptosystems to proxy multi‐signature scheme allowing parallel individual signing operation

Abstract

Even though there have been many research studies on proxy signature schemes, only Shao's proxy multi‐signature scheme is based on the factoring problem (FAC). Unfortunately, Shao's scheme requires sequential signing operations and strict order of the modulus. It is not practical and not efficient. We, therefore, based on RSA cryptosystems, propose new proxy‐protected mono‐signature and proxy‐protected multi‐signature schemes. In contrast to their counterparts, our scheme allows parallel signing operations and also improves the signers’ computational performance.     

基于变频器的一种协议转换接口设计

随着工厂自动化技术的发展,基于Profibus-DP 现场总线与Modbus协议的通信技术在国内外得到了广泛的应用。然而要实现两者之间数据转换却较为困难,原因是实现两者之间数据转换的产品相对较少。本文针对采用Modbus RTU协议通信的变频器,提供了一种Profibus- DP现场总线与Modbus协议之间转换的通信接口,主要阐述了该接口的软硬件设计方案,并重点介绍了实现通信接口可靠性与实时性的方法。实验结果证明了该设计方案的可行性。     

大型并网光伏电站监控系统设计与实现

监控系统在大型光伏电站中起着至关重要的作用。在分析光伏电站监控系统功能的基础上设计了监控系统的网络和组成结构,分别讨论了升压站内设备和光伏发电设备的CIM模型,Modbus与IEC 104的映射,以及AGC/AVC控制调节流程等关键技术。运行情况表明,依照此设计和实现的监控系统运行稳定可靠,完全满足大型光伏发电的监控要求。     

基于Modbus协议的PLC远程控制

在工业控制中,可编程控制器（PLC）作为工业控制装置已得到广泛的应用。采用高度实时性、高可靠性的PLC通信技术,就成为构成性能优异的自动控制系统的关键所在。Modbus协议是应用于电子控制器的一种通用语言。通过此协议,可实现控制器与其他设备(上位机)之间的远程通信。本设计就是以实验室现有的PLC为对象,实现基于Modbus协议的上位机对PLC的远程控制。实现上位机对PLC的远程控制,最理想的通信媒介就是通常所用的网线,即非屏蔽双绞线（UTP）。这就需要建立在以太网之上,即TCP/IP协议之上的Modbus通信协议。本次设计主要完成了完成了硬件连接及梯形图程序的编写,实现了控制器对输出线圈的控制,在建立PLC与上位机网络通信时,完成了对PLC通信模块的配置和PC机与PLC基于以太网的连接,采用Modbus TCP调试软件进行通信测试,测试结果表明上位机与台达PLC两个从站均可建立稳定的Modbus通信。     

一种有资源适应性的transcoding代理缓存机制

在基于transcoding代理的流媒体服务系统中,CPU和网络是两种潜在的瓶颈资源.本文提出了一种有资源适应性的transcoding代理缓存机制,统一考虑CPU和网络的资源需求,以提高系统的服务能力.首先推导了多版本缓存策略下网络收益和CPU收益的计算方法.通过引入一个时变的影响因子 α (t),给出了缓存系统聚合资源收益的表达.在此基础上给出了单个对象的缓存价值函数,并设计了RAC替换算法.实验表明RAC具有较好的资源适应性和系统吞吐率.     

对一种代理多重签名的安全分析

Zhou等人提出一种强代理多重签名方案,并声称该方案具有强不可伪造性和不可否认性.通过对Zhou的方案进行安全分析,指出该方案具有伪造性和否认性,并给出相应的攻击方法.通过对签名中R表示形式的限定给出两种改进方法来阻止相应的攻击.     

一种新的轻量级安全代理协议

随着网络技术的发展和广泛应用,在互联网环境下建立安全信道愈发显得重要.我们设计了一种采用TLSv1.3的握手协议框架的轻量级安全代理协议,在安全性的基础上提供了更好的隐蔽性和性能.代理程序的用户接口基于Socks5协议,保障了通用性.握手过程模拟TLS,将实际参数填充在TLSv1.3握手包内的随机区域和加密区域中来完成...     

一种新型无刷电动机驱动的自动开窗机设计与实现

直流开窗机的电刷磨损问题与消防组网问题,分别成为开窗机生产厂家两个急需解决的关键问题.其直接影响着开窗机的寿命和当前消防自动化智能水平的提高.针对当前开窗机存在的问题,改用无刷直流电动机进行电气驱动,充分利用无刷电动机内部的霍尔传感器进行位置检测,把开窗机设计成Modbus RTU单元,从总体性能上提高当前开窗机的性能,实现对开窗机的技术改进与网络控制.     

机房网络化管理

随着计算机数量的增加,机房的管理方式由以前的手工转变为网络管理模式。其中,通过对网络软件的使用,不仅大大降低了机房管理成本,而且增强了对计算机的维护与利用。