acSB: Anti-Collision Selective-Based Broadcast Protocol in CR-AdHocs

As a fundamental operation in ad hoc networks, broadcast could achieve efficient message propagations. Particularl y in the cognitive radio ad hoc network where unlicensed users have different sets of available channels, broadcasts are carried out on multiple channels. Accordingly, channel selection and collision avoidance are challenging issues to balance the efficiency against the reliability of broadcasting. In this paper, an anti-collision selective broadcast protocol, called acSB, is proposed. A channel selection algorithm based on limited neighbor information is considered to maximize success rates of transmissions once the sender and receiver have the same channel. Moreover, an anti-collision scheme is adopted to avoid simultaneous rebroadcasts. Consequently, the proposed broadcast acSB outperforms other approaches in terms of smaller transmission delay, higher message reach rate and fewer broadcast collisions evaluated by simulations under different scenarios.     

矿山酸性水中浸矿细菌的筛选及除铁效果

细菌浸矿在矿石综合利用和生态环境保护方面具有重要意义。从兖州煤矿酸性矿井水中筛选、分 离到1株具有嗜酸、氧化Fe2+的浸矿细菌,编号SKDYJ-1。通过对其16S rDNA 基因序列分析,发 现该菌株16S rDNA 基因序列与Pantoea agglomerans P1SAA（FJ611818）的同源性高达98% ,为嗜酸成团泛菌。对该菌株形态、生长特性、Fe2+氧化率进行了研究,结果表明：菌株 SKDYJ-1细胞呈杆状,革兰氏阴性,最适生长温度为30 ℃,在25 ℃、30 ℃以及35 ℃条件下培 养,菌株SKDYJ-1对Fe²⁺的最大氧化率分别为2.79%、6.52% 和5.59%,具有较高的浸矿能力。     

甲醇、丙酮及其二元混合工质脉动热管的启动特性

以甲醇、丙酮以及二者体积比1：1混合组成的甲醇/丙酮混合液为工质,对脉动热管在不同加热功率和充液率下的启动特性进行了实验研究,结果表明：在低加热功率下时,甲醇/丙酮混合工质的启动时间比丙酮长,比甲醇短,适当增加启动功率可以明显缩短脉动热管的启动时间,但是对丙酮及混合工质的启动温升影响不大;在60W高加热功率下时,3种工质的启动方式均为温度突变型,其中混合工质的启动时间最短,并且增加启动功率可以明显地提高混合工质脉动热管的启动温升;充液率对脉动热管的启动方式影响较为明显,丙酮和混合工质的启动温升均随着充液率的增加而逐渐减少,在中低充液率（≤50%）下,二者属于温度突变型启动,而在80%高充液率下,其启动方式变为温度平稳过渡型启动。     

宜宾地区土壤养分空间变异及其丰缺状况分析

为探明宜宾地区主要土壤养分含量状况,基于野外采集的676份土壤样品,运用经典统计方法、地统计学方法和GIS技术分析了该区域8种土壤养分指标的空间变异特征及其丰缺状况。结果表明,宜宾地区土壤有机质、全氮、全钾和缓效钾含量适宜,碱解氮含量丰富,而速效钾、全磷和有效磷含量缺乏。各养分指标块金效应在44.02%~81.93%;其中有效磷和速效钾的空间自相关性较弱,主要受随机因素影响。空间分布上,有机质含量总体呈现东南高、中部和北部低;全氮和碱解氮含量由西北、东南向中部区域下降;全磷呈南高北低趋势,有效磷呈斑块状分布;缓效钾由中部向西北和东南部逐渐下降;速效钾表现为西高东低,全钾与之相反。本研究结果为宜宾地区烤烟平衡施肥及种植规划提供了理论依据。     

Controlled Synthesis of Hollow Cu2‐xTe Nanocrystals Based on the Kirkendall Effect and Their Enhanced CO Gas‐Sensing Properties

This paper develops a facile solution‐based method to synthesize hollow Cu_2‐xTe nanocrystals (NCs) with tunable interior volume based on the Kirkendall effect. Transmission electron microscopy images and time‐dependent absorption spectra reveal the temporal growth process from solid copper nanoparticles to hollow Cu_2‐xTe NCs. Furthermore, the as‐prepared hollow Cu_2‐xTe NCs show enhanced sensitivity for the detection of carbon monoxide (CO), which is often referred to as the “silent killer”. The response and recovery time of the as‐prepared sensor for the detection of 100 ppm CO gas are estimated to be about 21 and 100 s, respectively, which are sufficient to render it a promising candidate for effective CO gas‐sensing applications. Such enhanced performance is achieved owing to the small grain size and large specific area of the hollow nanostructures. Therefore, the obtained hollow NCs based on the Kirkendall effect may have the potential as new functional blocks for high‐performance gas sensors.     

中国东北地区梅河盆地梅河组含煤地层层序格架、沉积体系及其聚煤规律

梅河盆地位于敦化—密山断裂带内,为中国东北地区古近系重要的断陷聚煤盆地,含煤层位主要为古近系梅河组下含煤段和上含煤段。通过野外踏勘、岩心和显微镜观察,识别出梅河盆地下含煤段和上含煤段主要发育扇三角洲相和湖泊相,并进一步识别出扇三角洲平原、扇三角洲前缘、浅湖及湖沼亚相,其中煤层主要聚集于扇三角洲平原以及湖沼环境中。在野外露头剖面、测井曲线、岩心特征及地球化学特征分析的基础上,对梅河组层序地层研究表明,梅河组下含煤段至上含煤段共发育3个三级层序,其中下含煤段发育在层序I中,上含煤段则在层序III中,每个三级层序均发育低水位体系域(LST)、水进体系域(TST)和高水位体系域(HST)。通过对研究区134口钻孔层序内沉积相统计分析,发现不同体系域中沉积相和煤层分布特征不同,湖沼聚煤环境主要发育在层序I中TST和HST中,而扇三角洲平原聚煤环境主要发育于层序I中LST和层序III中,在TST和HST中湖沼环境沉积的煤层厚度大、连续稳定,为梅河盆地经济可采煤层,在层序I的LST中和层序III中扇三角洲平原沉积的煤多数薄且不连续,不具备经济可采价值。     

电机电流分析法在机床类设备诊断中的应用研究

机床类设备传动链复杂,结构紧凑且封闭,对传动系统状态监测一直没有有效的分析办法,即使在噪声增大等恶劣情况下,常规的振动诊断方法也难以奏效.本文尝试用电流信号分析法,简称MCSA(Motor Current Signal Analysis),对机床状态进行测试和分析.通过电机电流信号的传动链齿轮谱特征分析,对其做出了正确评估,表明定子电流能很好地反映机床传动系统部件的运行状况.同时进行了多种运行工况的测试与试验,研究结论对机床类设备的生产制造和现场运行状态的分析提供了有效依据.     

The application of polynomial analyses to detect global vegetation dynamics during 1982–2012

Use of the normalized difference vegetation index (NDVI) to build long-term vegetation trends is one of the most effective techniques for identifying global environmental change. Trend identification can be achieved by ordinary least squares (OLS) analysis or the Theil–Sen (TS) procedure with a Mann–Kendall (MK) significance test, and these linear regression approaches have been widely used. However, vegetation changes are not linear, and thus the response of vegetation to global climate change may follow non-linear trends. In this article, a polynomial trend-fitting method, which uses stepwise regression and expands on previous research, is presented. With an improved fitting ability, this procedure may reveal trends that were concealed by linear fitting methods. Globally, the traditional TS-MK method reveals significant greening trends for 37.27% of vegetated land, and significant browning trends for 7.98%. Using the polynomial analysis, 34.62% of pixels were fitted by high-order trends. The significant greening trends covered up to 30% of cultivated land, thus indicating that cultivated vegetation may be increasing faster than natural vegetation. Significant vegetation browning mostly occurred in sparse vegetation areas, which suggests that vegetation growth may be more sensitive to climate change in arid regions. Our results show that use of polynomial analysis can help further elucidate global NDVI trends.     

基于B-LM圆环模型的NLOS信息约束单基站定位算法

针对当前室外蜂窝网多基站定位需要基站之间时间同步、数据同步的要求,以及NLOS环境造成的非服务区基站的信号可测性问题,该文提出基于B-LM圆环模型的NLOS信息约束单基站定位算法。首先根据散射体、目标和基站间的几何位置关系以及NLOS多路径信息构建定位方程,然后将定位方程转化为最小二乘优化问题,之后基于LM算法海森矩阵修正思想和拟牛顿2阶偏导构造思想提出B-LM算法,保证算法收敛于最优解,以得到目标位置。仿真结果表明,所提单基站定位算法能在宏蜂窝NLOS环境实现较高的定位精度。     

A flexible design framework for process systems under demand-side management

Demand response (DR) has been an appealing strategy for both residential and commercial/industrial customers of electricity due to the increasing penetration of renewable energy resources into the power grid and the deregulation of the energy markets. For industrial DR participants, the management of energy consumption along with the satisfaction of production expectations is generally referred to as demand-side management. Recent research in this area has focused mostly on process scheduling and capacity planning, especially for energy-intensive processes. This article presents a new direction through an optimization-based process design paradigm that allows for the potential reconfiguration of the process flow sheet in real time. Based on a case study of pump network design, a network superstructure is first defined, followed by a two-stage stochastic optimization model. The method of progressive hedging is used to solve the resulting mixed-integer stochastic programming problem. The results demonstrate that, under various scenarios, the reconfigurable design offers significant benefits compared to a fixed network structure in terms of total design cost and expected operating cost.