Maximum Data Generation Rate Routing Protocol Based on Data Flow Controlling Technology for Rechargeable Wireless Sensor Networks

For rechargeable wireless sensor networks,limited energy storage capacity,dynamic energy supply,low and dynamic duty cycles cause that it is unpractical to maintain a fixed routing path for packets delivery permanently from a source to destination in a distributed scenario.Therefore,before data delivery,a sensor has to update its waking schedule continuously and share them to its neighbors,which lead to high energy expenditure for reestablishing path links frequently and low efficiency of energy utilization for collecting packets.In this work,we propose the maximum data generation rate routing protocol based on data flow controlling technology.For a sensor,it does not share its waking schedule to its neighbors and cache any waking schedules of other sensors.Hence,the energy consumption for time synchronization,location information and waking schedule shared will be reduced significantly.The saving energy can be used for improving data collection rate.Simulation shows our scheme is efficient to improve packets generation rate in rechargeable wireless sensor networks.

Influence of Maximum Aggregate Size on Dynamic Size Effect of Concrete Under Low Strain Rates:Meso-scale Simulations

This study is to explore the influence of maximum aggregate size(MAS)on the failure and corresponding size effect of concrete materials under low strain rates.The failure process of concrete was simulated by the mesoscale numerical method considering the internal heterogeneity of concrete and strain rate effect.Based on the mesoscale method,the failure behavior of concrete specimens with different structural sizes and MAS was investigated.Also,the influence of MAS on the failure modes,nominal strength and corresponding size effect of concrete were studied at the meso-scale.The simulation results indicated that MAS has an obvious influence on the failure modes of concrete subjected to axial compressive and tensile loads.The nominal tensile strength increased as the MAS increased,while the nominal compressive strength increased first and then decreased as the MAS increases under quasi-static load.In addition,it was found that the size effect on nominal strength of concrete would be weakened with the increase of strain rate.When the applied strain rate reached 1 s^-1,the size effect on nominal strength of concrete disappeard.Moreover,the MAS has an ignorable influence on the dynamic size effect of concrete under uniaxial compression and tension.

Origin of Erosion and Hydraulic Problems of the San Roque Underground Arched Culvert Channel and Its Relationship with the Maximum Flow Rate and the Maximum Permissible Velocity

This work presents the hydrologic estimations of the hydraulic underground arched culvert channel (UACC) in Sabinal Basin, Chiapas, México and the hydrological problems associated with it, such as the erosion phenomenon and abrasion cavity formation in it. On the other hand, the maximum flows that the UACC could transport were analyzed, concluding that it no longer has the hydraulic capacity to transport the flow rate associated to return periods equal to or greater than five years and that maximum permissible velocity UACC’s bottom is 3 m/s.

Effects of site productivity on individual tree maximum basal area growth rates of Eucalyptus pilularis in subtropical Australia

Inventory data were available from 96 plots of even-aged,monoculture,tall-open forests of Eucalyptus pilularis Smith,aged 2-63 years,growing in sub-tropical regions along the east coast of Australia.A model was developed relating the maximum possible stem basal area growth rate of individual trees to their stem basal area.For any tree size,this maximum increased as site productivity increased.However,the size at which this maximum occurred decreased as productivity increased.Much research has shown that,at any stand age,trees of a particular stem basal area are taller on more productive sites than on less productive ones.Taller trees incur greater respiratory costs to ensure maintenance of the photo synthetic capacity of their canopies;this reduces their growth rates.It was concluded that trees with larger basal areas will have the maximum possible growth rate on a less productive site,whilst trees with smaller basal areas will have the maximum possible on a more productive site.The model developed may constitute the first stage of a complete individual tree growth model system to predict wood yields from these forests.

THE CONVERGENT RATE OF VISCOSITY METHOD FOR A VARIANT NON-ISENTROPIC SYSTEM OF POLYTROPIC GAS

In this short paper,we remove the restrictionγ∈(1,3]that was used in the paper"The rate of convergence of the viscosity method for a nonlinear hyperbolic system"(Nonlinear Analysis,1999,38:435-445)and obtain a global Holder continuous solution and the convergent rate of the viscosity method for the Cauchy problem of the variant nonisentropic system of polytropic gas for any adiabatic exponentγ>1.

Application of maximum rank distance codes in designing of STBC-OFDM system for next-generation wireless communications

Space-Time Block Coded(STBC)Orthogonal Frequency Division Multiplexing(OFDM)satisfies higher data-rate requirements while maintaining signal quality in a multipath fading channel.However,conventional STBCs,including Orthogonal STBCs(OSTBCs),Non-Orthogonal(NOSTBCs),and Quasi-Orthogonal STBCs(QOSTBCs),do not provide both maximal diversity order and unity code rate simultaneously for more than two transmit antennas.This paper targets this problem and applies Maximum Rank Distance(MRD)codes in designing STBCOFDM systems.By following the direct-matrix construction method,we can construct binary extended finite field MRD-STBCs for any number of transmitting antennas.Work uses MRD-STBCs built over Phase-Shift Keying(PSK)modulation to develop an MRD-based STBC-OFDM system.The MRD-based STBC-OFDM system sacrifices minor error performance compared to traditional OSTBC-OFDM but shows improved results against NOSTBC and QOSTBC-OFDM.It also provides 25%higher data-rates than OSTBC-OFDM in configurations that use more than two transmit antennas.The tradeoffs are minor increases in computational complexity and processing delays.

Non-Contact Method of Heart Rate Measurement Based on Facial Tracking

Image photoplethysmography can realize low-cost and easy-to-operate non-contact heart rate detection from the facial video, and effectively overcome the limitations of traditional contact method in daily vital sign monitoring. However, it is hard to obtain more accurate heart rate detection values under the conditions of subject’s facial movement, weak ambient light intensity and long detection distance, etc. In this article, a non-contact heart rate detection method based on face tracking is proposed, which can effectively improve the accuracy of non-contact heart rate detection method in practical application. The corner tracker algorithm is used to track the human face to reduce the motion artifact caused by the movement of the subject’s face and enhance the use value of the signal. And the maximum ratio combining algorithm is used to weight the pixel space pulse wave signal in the facial region of interest to improve the pulse wave extraction accuracy. We analyzed the facial images collected under different experimental distances and action states. This proposed method significantly reduces the error rate compared with the independent component analysis method. After theoretical analysis and experimental verification, this method effectively reduces the error rate under different experimental variables and has good consistency with the heart rate value collected by the medical physiological vest. This method will help to improve the accuracy of non-contact heart rate detection in complex environments.

Application of the Bayes’ theory to the failure rate evaluation of electrical apparatus

The Weibull distribution has been widely used in reliability fields. A mixed Weibull distribution represents a popu- lation that consists of several Weibull subpopulations. In this paper, a new approach which combines the least-squares method with Bayes’ theorem, takes advantage of the parameter estimation for single Weibull distribution is developed to estimate the pa- rameters of each subpopulation. The estimates given by this paper also satisfy the maximum likelihood equation. The estimates of the failure rate of the mixed Weibull population are given. An actual test data is computed by using the proposed method. The Kolmogorov-Smirnov goodness-of-fit test turns out that the proposed method yields more accurate result.

Simulation Methods of Stochastic Volatility Interest Rate Term Structure

A term structure model bearing features of stochastic volatility and stochastic mean drift with jump （SVJ-SD model for short） is built in the paper to describe the stochastic behavior of interest rates.Based on sample data of an interest rate of national bond repurchase,maximum likelihood （ML）,linear Kalman filter and efficient method of moments （EMM） are used to estimate the model.While ML works well for simple models,it may lead to considerable deviation in parameter estimation when dynamic risks of interest rates are considered in them.Linear Kalman filter is a tractable and reasonably accurate technique for estimation cases where ML was not feasible.Moreover,when compared with the first two approaches,using EMM can obtain better parameter estimates for complex models with non-affine structures.

Recovery Capacity, Haemodynamic and Blood Lactate Changes during Training and Competition in Elite Congolese Karate Athletes

Background: Rare are the studies which treated the effect of training and successive fights of karate on haemodynamic and blood lactate concentrations responses. Objectives: To evaluate and analyze the aerobic capacity of elite Congolese karate athletes, as well as their haemodynamic and blood lactate concentrations responses changes during Ruffier test and stimulated competition. Methods: Twelve karate athletes (6 seniors and 6 juniors) took part in the study. These karate athletes were selected within the national karate teams (senior and junior) of Congo-Brazzaville. Anthropometric, bioenergetic and haemodynamic (HR, SBP, DBP) parameters and blood lactate [La] concentrations were measured at rest, immediately after the end of Ruffier test and each fight (n = 3). Results: Peak aerobic power (PAP) and maximum oxygen uptake (VO2 max) values averaged 437 ± 23 watts and 57.61 ± 2.2 ml/kg/mn, values varying as function as age division (senior vs junior). The recovery index was 5.4 ± 3.4 for juniors and 6.8 ± 3.2 for seniors. SBP, HR and [La] concentrations increased significantly during fights, compared to the resting values. HRmax was 182.3 ± 1.6 bpm (89% theoretical HRmax) for seniors and 182.0 ± 13.5 bpm (86% theoretical HRmax) for juniors. Peak [La] concentrations were 10.3 ± 1.5 mmol/l for seniors and 10.8 ± 1.2 mmol/l for juniors. Conclusion: Congolese karate athletes call upon high levels of the anaerobic and aerobic capacities. The karate training program in Congo should emphasize more gold improvising lower body anaerobic power and endurance.

Comparative Study of the Effect of Shading Rate on the Electrical Parameters of CIGS and CdTe/CdS Solar Modules

In this paper, a comparative study of the maximum power on the shading rate on the maximum power of thin film PV modules. Thus two thin film PV modules of type Copper indium gallium selenide, CIGS, of 90W power and a CdTe (Cadmium telluride)/CdS (Cadmium sulfide) module, of maximum power 75 W. These modules, reference SN-CIGS90 and CX3 75 were tested under the conditions of the installation site to ensure their proper functioning and to determine the initial values of electrical parameters before shading. The results obtained are as follows: for the CIGS: Pm (80.717 W);Vco (23.06 V), Icc (3.5 A) and for the CdTe:Pm (54.914 W);Vco (35.52 V), Icc (1.546 A). After this characterization test, the modules are exposed to real operating conditions at the Center for Study and Research on the renewable energy (CERER), Cheikh Anta Diop University in Dakar. Four types of shading are performed on each module with the same mask: partial shading at 25%, 50%, 75% and complete shading at 100%. The comparison of the variation rates obtained on the experimental values of the 4 types of shading carried out on each module, shows that, the phenomenon of shading constitutes an environmental factor which influences negatively the maximum power of the thin film PV modules. But this reduction depends on the surface of the shaded module, the nature of the mask but also the technology used. Indeed, for a shading of 25% of the surface of the two modules, we note a reduction of 21.32% of power for the CIGS, against 40.53% for the CdTe/CdS, that is to say a difference which approaches 20%.

Processing of Landsat 8 Imagery and Ground Gamma-Ray Spectrometry for Geologic Mapping and Dose-Rate Assessment, Wadi Diit along the Red Sea Coast, Egypt

Maximum Likelihood (MLH) supervised classification of atmospherically corrected Landsat 8 imagery was applied successfully for delineating main geologic units with a good accuracy (about 90%) according to reliable ground truth areas, which reflected the ability of remote sensing data in mapping poorly-accessed and remote regions such as playa (Sabkha) environs, subdued topography and sand dunes. Ground gamma-ray spectrometric survey was to delineate radioactive anomalies within Quaternary sediments at Wadi Diit. The mean absorbed dose rate (D), annual effective dose equivalent (AEDE) and external hazard index (Hex) were found to be within the average worldwide ranges. Therefore, Wadi Diit environment is said to be radiological hazard safe except at the black-sand lens whose absorbed dose rate of 100.77 nGy/h exceeds the world average. So, the inhabitants will receive a relatively high radioactive dose generated mainly by monazite and zircon minerals from black-sand lens.

A NEW DESIGN METHOD OF CDMA SPREADING CODES BASED ON MULTI-RATE UNITARY FILTER BANK

It is well-known that the multi-valued CDMA spreading codes can be designed by means of a pair of mirror multi-rate filter banks based on some optimizing criterion. This paper indicates that there exists a theoretical bound in the performance of its circulating correlation property, which is given by an explicit expression. Based on this analysis, a criterion of maximizing entropy is proposed to design such codes. Computer simulation result suggests that the resulted codes outperform the conventional binary balanced Gold codes for an asynchronous CDMA system.

基于ML估计的高动态GNSS信号快速捕获检测方法

针对高动态环境下GNSS因频域带宽增加导致捕获难度增大的问题,分析了接收端数字中频采样信号的传输特性及复基带信号经FFT模块处理后的相关峰的检测,提出了基于极大似然(ML)估计的高动态GNSS信号快速捕获检测方法。首先,根据随机信号的统计理论建立二元假设检验条件,构建了奈曼-皮尔逊准则下的GNSS信号捕获判决门限模型;其次,通过判决量的统计特性对等效高斯白噪声方差进行ML估计,根据其估计值计算捕获判决门限,其中通过虚警率的量化放大处理,解决了判决量样本值的增加带来的估计偏差问题;最后,对不同高动态条件下北斗B3I信号进行了捕获检测仿真实验。结果表明采用ML估计方法确定捕获判决门限从而提高高动态GNSS信号捕获的检测方法对高动态适应范围较宽,其频移捕获精度与SINS信息辅助捕获相当,比序贯检测算法提高约28%以上,相同条件下具有更快的平均捕获检测速度。

小麦叶片和冠层尺度气体交换模型关键参数的季节变化特征

本文从叶片和冠层尺度入手,采用手持式光合仪和涡动相关法,分析确定C3作物春小麦和冬小麦气体交换模型关键参数随季节变化的特征。结果表明:春小麦叶片尺度最大羧化速率和最大电子传递速率在生育末期快速减小,其他阶段差异不显著,但二者之比随发育期变化相对稳定,均值为2.2;春小麦生长季叶片气孔导度模型斜率在9~11间变动,均值为9.7。冬小麦冠层尺度最大羧化速率和最大电子传递速率随发育期呈抛物线变化,但二者之比相对稳定,均值为1.43;冬小麦冠层导度模型斜率在不同年份不同季节变化无明显规律,整个生育期围绕均值12波动。本研究论证了表征作物光合能力的参数随生育期变化以及气孔导度模型斜率相对稳定的特征。可为陆气相互作用过程分析以及生态系统碳—水循环模拟提供参数化依据。

联合RIS子块与接收天线的索引调制方案性能分析

利用大量无源反射器件设计的可重构智能表面(RIS),具有拓展无线通信覆盖范围、降低系统成本/功耗和提升未来通信系统性能的优势;而索引调制(IM),通过激活通信资源的子集可实现信息的隐性传输,有望为无线通信带来更高的频谱效率和能量效率,因此,为进一步提升未来无线通信系统的性能,该论文融合RIS与IM技术,提出一种联合RIS子块与接收天线的IM方案。在该方案中,按照相邻原则,将RIS反射元件分割为若干子块,进而利用RIS子块索引与接收天线索引同时实现附加信息传递,即对待传输比特序列,将其分割为三部分,其中第一部比特被调制为星座符号,第二部分用于指示RIS子块划分,第三部分用于指示接收天线索引;在此基础上,根据最大似然(ML)检测的成对错误概率(PEP)解析形式,分四种情况,从理论上推导出对应的矩母函数(MGF),得到无条件PEP的解析表达式,最后得到该方案ML检测的平均误码率(ABER)性能上界。仿真结果表明,与现有RIS辅助的IM方案相比,无须增加额外频谱资源,所提方案的系统可达速率和系统差错性能方面均具有一定优势;同时,验证了ML检测的ABER上界具备严格一致性。

基于能量原理不同含水率下煤岩体变形破坏能量损伤演化机制

为探究不同含水率下煤岩体在变形破坏过程中的能量演化规律与损伤演化特征,对双马一矿煤岩体开展了在不同含水率条件下单轴压缩试验,基于能量计算及最小耗能原理,分析不同含水率下煤岩体能量耗散特征及损伤演化机制,结果表明:不同含水率下煤岩体力学性质不同,峰值应变与含水率呈正相关,抗压强度、弹性模量与含水率呈负相关;煤岩体含水率越高,其在峰值处弹性应变能及破坏吸收总应变能越小,耗散能占总应变能比例越高;基于最小耗能原理建立的损伤本构模型表明:随着煤岩体含水率增加,损伤门槛值逐渐降低;干燥状态下,煤岩体在应力峰值处损伤变量分别为0.36、0.28,当含水率增至自然状态时,煤岩体在应力峰值处损伤变量值分别下降0.09、0.18,但当含水率增至饱水状态时,煤岩体在应力峰值处损伤变量值反而分别大幅度上升0.102、0.49,总体呈先减后增的发展趋势;进一步建立了不同含水率煤岩损伤应变能释放率演化模型,低含水率煤岩较干燥煤岩的最大损伤应变能释放率大幅度下降,降幅分别为45.61%、31.29%,而随着含水率增加至饱水状态,其最大损伤应变能释放率增大幅度较平缓,分别为3.08%、8.80%,表明煤岩破坏剧烈程度并未大幅度增加。研究成果对煤岩矿柱水害预测评价与岩石损伤评估具有一定参考意义。

大功率燃料电池建模与电压一致性分析

随着燃料电池堆朝着大功率发展,其工作时单体间的不一致性更加明显,长时间处于恶劣工作条件的单体寿命会明显短于其他单体,并导致电池堆的寿命大幅缩减。为探究不同运行参数对大功率燃料电池单体工作性能一致性的影响规律,首先,建立了包括流体网络模型、燃料电池电压模型和燃料电池热阻模型三个部分的110 kW大功率燃料电池模型。其次,开展燃料电池稳态试验,对所建立的燃料电池模型进行试验验证,仿真与试验结果误差在5%以内。最后,基于模型仿真,以电压最大偏差率为评价指标,分别探究工作电流、冷却水流量和冷却水进口温度三个运行参数对燃料电池电压一致性的影响规律。仿真结果表明,工作电流对燃料电池单体电压一致性的影响程度更大,其次是冷却水进口温度,最后是冷却水流量。本研究有助于大功率燃料电池发动机的结构优化设计以及为热管理控制策略开发提供指导。

语义通信的数学理论

自从1948年经典信息论诞生以来,在其指导下,现代通信技术已经逼近了理论性能极限,例如信息熵H(U)、信道容量C=max_(p(x))I(X;Y)以及率失真函数R(D)=min_(p(x|x):Ed(x,x)≤D)I(X;X)。长期以来,由于经典信息论只研究语法信息,限制了通信科学的进一步发展。近年来,研究语义信息处理与传输的通信技术获得了学术界的普遍关注,语义通信开辟了未来通信技术发展的新方向,但还缺乏一般性的数学指导理论。为了解决这一难题,构建了语义信息论的理论框架,对语义信息的度量体系与语义通信的理论极限进行了系统性阐述。首先,通过深入分析各类信源的数据特征,以及各种下游任务的需求,总结归纳出语义信息的普遍属性——同义性。由此指出语义信息是语法信息的上级概念,是许多等效或相似语法信息的抽象特征,表征隐藏在数据或消息背后的含义或内容。将语义信息与语法信息之间的关系命名为同义映射,这是一种“一对多”映射,即一个语义符号可以由许多不同的语法符号表示。基于同义映射f这一核心概念,引入语义熵H_(s)(U)作为语义信息的基本度量指标,表示为信源概率分布与同义映射的泛函。在此基础上,引入上/下语义互信息I^(s)(X;Y)(I_(s)(X;Y)),语义信道容量C_(s)=max_(f_(xy))max_(p_((x)))I^(s)(X;Y)以及语义率失真函数R_(s)(D)=min_({f_(x),f_(x)})min_(p(x|x):Ed_(s)(x,x)≤D)I_(s)(X;X),从而构建了完整的语义信息度量体系。这些语义信息度量是经典信息度量的自然延伸,都由同义映射约束,如果采用“一对一”映射,则可以退化为传统的信息度量。由此可见,语义信息度量体系包含语法信息度量,前者与后者具有兼容性。其次,证明了3个重要的语义编码定理,以揭示语义通信的性能优势。基于同义映射,引入新的数学工具——语义渐近均分(AEP),详细探讨了同义典型序列的数学性质,并应用随机编码和同义典型序列译码/编码,证明了语义无失真信源编码定理、语义信道编码定理和语义限失真信源编码定理。类似于经典信息论,这些基本编码定理也都是存在性定理,但它们指出了语义通信系统的性能极限,在语义信息论中起着关键作用。由同义映射和这些基本编码定理可以推断,语义通信系统的性能优于经典通信系统,即语义熵小于信息熵H_(s)(U)≤H(U),语义信道容量大于经典信道容量C_(s)≥C,以及语义率失真函数小于经典率失真函数R_(s)(D)≤R(D)。最后,讨论了连续条件下的语义信息度量。此时,同义映射转换为连续随机变量分布区间的划分方式。相应地,划分后的子区间被命名为同义区间,其平均长度定义为同义长度S。特别是对于限带高斯信道,得到了一个新的信道容量公式C_(s)=B log[S^(4)(1+P/N_(0)B)],其中,平均同义长度S表征了信息的辨识能力。这一容量公式是经典信道容量的重要扩展,当S=1时,该公式退化为著名的香农信道容量公式。综上所述,语义信息论依据同义映射这一语义信息的本质特征,构建了语义信息的度量体系,引入新的数学工具,证明了语义编码的基本定理,论证了语义通信系统的性能极限,揭示了未来语义通信的巨大性能潜力。

耦合叶肉导度的陆面过程模型最大叶肉导度参数的敏感性分析

陆面过程模型添加叶肉导度能有效改善模型模拟的CO_(2)施肥效应精度,但叶肉导度模拟受最大叶肉导度参数取值的影响,优化模型中最大叶肉导度参数是改进陆面过程模型叶肉导度和CO_(2)施肥效应模拟的重要途径。以EALCO(Ecological Assimilation of Land and Climate Observations)模型为例添加叶肉导度,通过人为改变最大叶肉导度值的取值,分析模型输出结果对最大叶肉导度的响应,揭示最大叶肉导度参数在模型中的敏感性,并与已有研究结果或观测数据比较,探讨耦合叶肉导度的陆面过程模型最大叶肉导度参数优化的途径。模拟试验以美国哈佛森林典型温带落叶阔叶林生态监测站(US-Ha1 site, Harvard Forest Environmental Monitoring site)数据为驱动。结果显示:(1)随最大叶肉导度增加,总初级生产力(GPP, Gross Primary Production)模拟精度增加,但最大叶肉导度取值大于1.0 mol m^(-2)s^(-1)后模拟精度改善有限,最大叶肉导度小于1.0 mol m^(-2)s^(-1)时GPP模拟精度对最大叶肉导度变化响应敏感;(2)证实了叶肉导度与气孔导度之间存在明显线性关系,最大叶肉导度取值的变化能明显影响这种线性关系的斜率。当最大叶肉导度取值从0.5 mol m^(-2)s^(-1)增加到1.2 mol m^(-2)s^(-1)时,气孔导度与叶肉导度的比值从0.75左右降至0.36,这个结果表明,通过明确某一植被功能型叶肉导度与气孔导度比值,可以间接确定模型最大叶肉导度的合理取值范围;(3)证实了陆面过程模型添加叶肉导度能改进CO_(2)施肥效应模拟精度,最大叶肉导度值能影响施肥效应模拟结果,当最大叶肉导度高于0.57 mol m^(-2)s^(-1)后,随最大叶肉导度增加,模拟GPP随大气CO_(2)浓度增加的增长率呈下降趋势;(4)在月尺度上叶肉导度模拟对最大叶肉导度值的敏感性随不同生长季而不同,在生长盛期的7、8月份最大叶肉导度对叶肉导度模拟结果影响最大,其次是5、6、9月份等生长次盛期,其他月份的影响较小。