Existence of Monotone Positive Solution for a Fourth-Order Three-Point BVP with Sign-Changing Green’s Function

This paper is concerned with the following fourth-order three-point boundary value problem , where , we discuss the existence of positive solutions to the above problem by applying to the fixed point theory in cones and iterative technique.

Vegetation Change Prediction with Geo-Information Techniques in the Three Gorges Area of China

A computerized parametric methodology was applied to monitor, map, and estimate vegetation change in combination with '3S' (RS-remote sensing, GIS-geographic information systems, and GPS-global positioning system) technology and change detection techniques at a 1:50000 mapping scale in the Letianxi Watershed of western Hubei Province, China. Satellite images (Landsat TM 1997 and Landsat ETM 2002) and thematic maps were used to provide comprehensive views of surface conditions such as vegetation cover and land use change. With ER Mapper and ERDAS software, the normalized difference vegetation index (NDVI) was computed and then classified into six vegetation density classes. ARC/INFO and ArcView software were used along with field observation data by GPS for analysis. Results obtained using spatial analysis methods showed that NDVI was a valuable first cut indicator for vegetation and land use systems. A regression analysis revealed that NDVI explained 94.5% of the variations for vegetation cover in the largest vegetation area, indicating that the relationship between vegetation and NDVI was not a simple linear process. Vegetation cover increased in four of areas. This meant 60.9% of land area had very slight to slight vegetation change, while 39.1% had moderate to severe vegetation change. Thus, the study area, in general, was exposed to a high risk of vegetation cover change.

Investigating the Use of Remote Sensing and GIS Techniques to Detect Land Use and Land Cover Change: A Review

The accuracy of change detection on the earth’s surface is important for understanding the relationships and interactions between human and natural phenomena. Remote Sensing and Geographic Information Systems (GIS) have the potential to provide accurate information regarding land use and land cover changes. In this paper, we investigate the major techniques that are utilized to detect land use and land cover changes. Eleven change detection techniques are reviewed. An analysis of the related literature shows that the most used techniques are post-classification comparison and principle component analysis. Post-classification comparison can minimize the impacts of atmospheric and sensor differences between two dates. Image differencing and image ratioing are easy to implement, but at times they do not provide accurate results. Hybrid change detection is a useful technique that makes full use of the benefits of many techniques, but it is complex and depends on the characteristics of the other techniques such as supervised and unsupervised classifications. Change vector analysis is complicated to implement, but it is useful for providing the direction and magnitude of change. Recently, artificial neural networks, chi-square, decision tree and image fusion have been frequently used in change detection. Research on integrating remote sensing data and GIS into change detection has also increased.

The mechanism and clinical effectiveness of the six-step Chinese Daoyin technique on hemiplegic patients with drop-foot

Objective: The aim of this study was to improve the Chinese Daoyin technique (physical and breathing exercises), which is an ancient rehabilitation method, to elevate its effect and to standardize its operational procedure. Methods: Based on the ancient Chinese Daoyin technique, a six-step method was developed including: 1) motion imagination and imitation;2) mental and breathing regulation;3) target point determination;4) motion percussion;5) motion persistence;6) relaxation. Sixty drop-foot patients who suffered from hemiparesis after a stroke were randomly divided into the experimental group and the control group. Functional evaluation including Fugl-Meyer assessment score, Lovett manual muscle test (MMT), active range of motion of the ankle joint and electromyography were performed before and after the training course. The data were analyzed using the statistical software SPSS 12.0. Results: The differences between the two groups were significant. The effectiveness of the six-step group was significantly better than the effectiveness of the control group. Conclusion: The six-step method of the Chinese Daoyin technique is an effective rehabilitation training method for drop-foot in stroke patients with hemiparesis.

RESIDENCE TIME DISTRIBUTION STUDIES WITH TRACER EXPERIMENTS:IMPULSE INJECTION VERSUS STEP CHANGE OF FEED

1 INTRODUCTIONThe popularly used axial dispersion model is mathematically expressed by aone-dimensional partial differential

Assessment of water resources in Yarmouk River Basin using geospatial technique during the period 1980–2020

It is common knowledge that Yarmouk River Basin(YRB)is shared between Jordan and Syria.Management of YRB trans-boundary water resources is attracting increasing interest because it is a strategic water resource for the riparian countries.Actually,lack of sharing information regarding hydrological flows and basin’s water management between partners’countries makes it difficult to distinguish between natural and man-made factors affecting the water body.Therefore,this study seeks to address and assess the main on-site changes that exert on YRB.Geospatial technique and arithmetic equations were combined to carry out an assessment of the changes on water resources in YRB.Data,information and field measurements of the basin were aggregated,compiled and presented to determine the extent of changes during the period 1980-2020.Remarkable findings showed that precipitation amount in the basin significantly declined during the period 1980-2020 in particularly after the year 1992.Pumping rate of groundwater was 550 x 103 m3/a,exceeding the basin’s safe yield.Draw down of static groundwater level over time approached the value of-3.2 m/a due to the over abstraction in the aquifer body.Additionally,the evaporation rate reached more than 99%in some regions in the basin.Moreover,the number of private wells has increased from 98 wells in 1980 to 126 wells in 2020,showing the excessive extraction of groundwater.These findings indicate that the study area is subjected to a considerable groundwater depletion in the near future due to extensive abstraction,continuous drilling of illegal wells and decreased annual precipitation under the shadow of the rapid population growth and continuous influx of refugees.Therefore,decision makers-informed scenarios are suggested in the development of water resource portfolios,which involves the combination of management and infrastructural actions that enhance the water productivity of the basin.Further studies are recommended to evaluate the on-site changes on water resources in YRB in collaboration with riparian countries and to establish monitoring system for continuous and accurate measurements of the basin.

Method for differential phase delay resolution of phase referencing VLBI technique and its experimental verification

The phase referencing Very Long Baseline Interferometry(VLBI)technique is a newly developed tool to measure the angular position of a deep space exploration probe in the plane-of-the-sky.Through alternating observations between the probe and a nearby reference radio source,their accurate relative angular separation can be obtained from the radio images generated by this technique.To meet the requirements of the current orbit determination software,differential delay should be firstly derived from those radio images.A method to resolve the differential phase delay from the phase referencing VLBI technique is proposed in this paper,and as well the mathematical model for differential phase ambiguity resolution is established.This method is verified with practical measurement data from the Chang’E-3 mission.The differential phase delay between the Chang’E-3 lander and rover was derived from the phase referencing VLBI measurements,and was then imported into the Shanghai astronomical observatory Orbit Determination Program(SODP)to calculate the position of the rover relative to the lander on the lunar surface.The results are consistent with those acquired directly from radio images,indicating that the differential phase ambiguity has been correctly resolved.The proposed method can be used to promote applications of the phase referencing VLBI technique in future lunar or deep space explorations,and more accurate orbit determination becomes promising.

Spatiotemporal Analysis of Urban Sprawl and Its Contributions to Climate and Environment of Peshawar Using Remote Sensing and GIS Techniques

This research study predominantly emphases on spatiotemporal extensions of urban area of Peshawar;its adverse impacts and contributions to climate and environment during 1931 to 2011. To probe these interventions, meteorological data, Satellite’s temporal imagery of Landsat ETM+ and TM, anthropogenic and demographic secondary data were congregated. In relation to map out land cover changes, maximum likelihood classification algorithm and followed by change detection techniques were applied to study area. The outcome of this process was further subjected through Geographic Information System (GIS) overlay analysis which suggested a clear straggle in urban area. Auxiliary data (Population growth rate, transportation, electricity connections, etc.) also support the fact of urban area extension. This study proposes that severs contributions of massive heat energy and CO2 have been added to local climate and environment ensuing substantial increment in temperature drawn out from the trends. Consequently, Remote Sensing, GIS and allied data were found to be effective to gauge such variations. To eliminate anomalies in sprawl and environment, few suggestions and recommendation are made in latter part of this study.

Direct Digital Frequency Control Based on the Phase Step Change Characteristic between Signals

We present a new digital phase lock technology to achieve the frequency control and transformation through high precision multi-cycle group synchronization between signals without the frequency transformation circuit. In the case of digital sampling, the passing zero point of the phase of the controlled signal has the phase step characteristic, the phase step of the passing zero point is monotonic continuous with high resolution in the phase lock process, and using the border effect of digital fuzzy area, the gate can synchronize with the two signals, the quantization error is reduced. This technique is quite different from the existing methods of frequency transformation and frequency synthesis, the phase change characteristic between the periodic signals with different nominal is used. The phase change has the periodic phenomenon, and it has the high resolution step value. With the application of the physical law, the noise is reduced because of simplifying frequency transformation circuits, and the phase is locked with high precision. The regular phase change between frequency signals is only used for frequency measurement, and the change has evident randomness, but this randomness is greatly reduced in frequency control, and the certainty of the process result is clear. The experiment shows that the short term frequency stability can reach 10-12/s orders of magnitude.

基于多线程加速的STEP标准并行解析算法

当前CAD软件加载大型STEP中性文件时速度慢,其效率瓶颈关键在于其解析算法.针对基于单线程的中性标准解析算法已经远远不能满足当前CAD应用需求的问题,提出了一种基于多线程的分层并行数据解析算法,利用当前主流CPU都采用的多核并行架构,大幅提升了STEP文件解析效率.根据模型体中数据的分层特性,算法利用线程池对各层数据解析进行并行加速.文中算法已经在开源几何引擎OpenGE中实现.与OpenCASCADE的对比实验验证了文中算法的有效性.实验结果表明,算法的并行解析程序运行速度相比串行解析程序运行速度提升至原算法的2倍,比OpenCASCADE解析算法快50%.

治疗脾胃病的含救必应药对对溃疡性结肠炎的治疗作用

目的分析治疗脾胃病的含救必应药对对溃疡性结肠炎(UC)的治疗作用。方法(1)在中国知网数据库和万方数据知识服务平台中检索使用救必应治疗脾胃病的临床研究,收集其临床处方。应用数据挖掘技术分析治疗脾胃病的含救必应核心药对。(2)选择90只小鼠,将其随机分为正常组、模型组、救必应组及6组救必应药对组,每组10只。除正常组外,给予其余组小鼠饮用3%葡聚糖硫酸钠以建立UC模型,同时给予各给药组小鼠灌胃1.8 g/kg的相应药物,连续灌胃6 d,1次/d。在实验期间记录各组小鼠的一般症状,实验第7天观察其结肠外观、病理改变,检测其结肠组织Occludin蛋白、抗黏蛋白2(MUC2)、ATOH1蛋白的表达水平。结果(1)共获得6组含救必应的核心药对,分别为救必应-白芍、救必应-白术、救必应-茯苓、救必应-蒲公英、救必应-柴胡、救必应-党参。(2)与正常组比较,模型组小鼠的结肠长度缩短,体重下降率、疾病活动指数(DAI)及肺脏系数升高,结肠组织中MUC2、ATOH1和Occludin的蛋白表达水平降低(P<0.05)。与模型组相比,救必应-党参组小鼠体重下降率降低,救必应组、救必应-白芍组及救必应-党参组小鼠的结肠长度增加,救必应组、救必应-茯苓组及救必应-党参组小鼠的DAI降低,救必应组及救必应-白芍组小鼠的肺脏系数降低(P<0.05);救必应组及救必应-白芍组、救必应-柴胡组、救必应-党参组小鼠结肠组织黏膜下层水肿及炎症细胞浸润有所改善,救必应-白术组、救必应-茯苓组、救必应-蒲公英组小鼠结肠的黏液屏障损伤有所改善;救必应组MUC2、ATOH1和Occludin的蛋白表达水平上调,救必应-白术组、救必应-茯苓组、救必应-蒲公英组和救必应-党参组MUC2的蛋白表达水平上调,救必应-白芍能组ATOH1的蛋白表达水平上调,救必应-白术组Occludin的蛋白表达水平上调(P<0.05)。与救必应组相比,救必应-党参组的结肠长度增加,救必应-党参组及救必应-白芍药组对结肠病理改变的改善作用更为明显,救必应-白术组MUC2的蛋白表达水平更高(P<0.05)。结论救必应治疗脾胃病常用配伍药物为白芍、白术、茯苓、蒲公英、柴胡和党参。大多数含救必应药对可不同程度地改善UC小鼠模型的一般症状、病理表现及黏膜屏障蛋白的表达,其中,救必应-党参药对在改善结肠短缩及结肠病理改变方面均优于单用救必应,而救必应-白术药对在上调MUC2蛋白表达方面优于单用救必应。

基于阶梯阻抗谐振器的双频宽带滤波功分器

为了更好地满足无线通信系统对多功能、多频段射频前端器件的要求,提出了一种基于阶梯阻抗谐振器的双频宽带滤波功率分配器。首先,使用单个T形谐振器实现双频滤波单元,同时采用阶梯阻抗技术引入了单独可调的高次模用于展宽双频功分器的高频通带带宽;其次,利用枝节加载技术实现额外谐振模式的引入,展宽了双频滤波功分器低频通带带宽;为了实现小型化设计,对部分微带线进行弯折,使得整个电路结构更加紧凑。此外,利用T形谐振器自身的滤波特性和在微带馈线上加载的开路枝节,在带外产生四个可控的传输零点,提高了通带外选择性;通过在微带馈线上加载扇形枝节和在输出端口引入隔离电阻,有效改善了滤波功分器的带内阻抗匹配效果和隔离度。为了进一步验证,对所提出的滤波功分器进行了加工和测试。该滤波功分器的中心频率为2.83 GHz和4.87 GHz,相对带宽分别为10.6%和11.7%,通带隔离度均大于14.5 dB。测试和仿真结果基本一致。

桑干河流域淤地坝沉积泥沙特征及其来源解析

[目的]为查明桑干河流域的泥沙主要策源地和侵蚀产沙变化。[方法]选取阳原县高墙乡典型淤地坝沉积泥沙为研究对象,利用复合指纹识别技术,测定沉积泥沙及其源地的土壤粒径、SOC、TN、137 Cs、低频质量磁化率等9种指纹因子,研究了不同淤积阶段的泥沙策源地及坝控小流域侵蚀产沙演变规律。[结果](1)沉积泥沙中137 Cs平均含量较低,与沟壁土壤无显著差异(p>0.05),但极显著小于林草地和耕地的137 Cs含量(p<0.01),这指示淤地坝沉积泥沙主要来源于沟壁;(2)由于沟壁中大部分137 Cs含量低于检出限,137 Cs较好地指示泥沙主要来源沟谷地中的沟壁,但难以用于小流域多种策源地的判别,经Kruskal-Wallis H非参数检验和多元逐步判别分析筛选,确定TN+X lfb+SOC构成最佳指纹因子组合,有效地判别小流域2006—2017年泥沙源地的平均贡献率为沟壁(82.68%±8.20%)>耕地(15.36%±8.46%)>林草地(1.96%±0.33%);(3)在小流域侵蚀产沙过程中,沟壁长期是主要的泥沙贡献区,林草地对侵蚀性降雨的响应较弱,耕地在极端暴雨发生时其泥沙贡献率显著上升。[结论]137 Cs核素示踪技术有效地适用于该区小流域主要泥沙策源地判别,复合指纹技术则可以更好地厘定多元泥沙策源地。沟蚀引起的沟壁崩塌是桑干河流域土壤侵蚀严重的主要原因。

杨树人工林复合经营模式对土壤N_(2)O与CO_(2)排放的影响

为探讨杨树人工林复合经营模式对土壤温室气体排放的影响,基于11年生“南林-895杨”(Populus×euramericana‘Nanlin-895’)人工林,设置纯林、林下种植麦冬(Ophiopogon japonicas)和林下养鸡3种复合经营模式,采用静态箱-气相色谱法每月测定土壤N_(2)O和CO_(2)排放通量,同时测定土壤温湿度,分析复合经营模式对土壤N_(2)O和CO_(2)排放和产量的影响及与相关影响因子的关系。结果表明:不同复合经营模式林下土壤温、湿度存在显著差异;不同杨树复合经营模式间,土壤N_(2)O和CO_(2)排放速率动态变化与年累积排放量存在显著差异,杨树林下种植麦冬的土壤N_(2)O年累积排放量最高,为233.47 mg·m^(-2)·a^(-1),而林下养鸡的土壤CO_(2)年累积排放量最高,达2328.87 g·m^(-2)·a^(-1)。总体来看,不同复合经营模式林地土壤温室气体(N_(2)O和CO_(2))年累积排放量为林下养鸡>林下种植麦冬>杨树纯林;土壤温、湿度对土壤CO_(2)和N_(2)O排放速率有显著影响,其中,土壤CO_(2)排放速率与土壤温度之间呈显著线型相关,而与土壤湿度呈现抛物线型关系;土壤N_(2)O排放速率与土壤温、湿度的关系均可用抛物线型关系来描述。综上所述,不同杨树复合经营模式改变了林地土壤的温、湿度,进而对温室气体排放产生了显著的影响。从1年的研究结果看,种植麦冬和养鸡的杨树人工林林地土壤温室气体的年累积排放量高于纯林,表明林农复合经营增加了土壤温室气体的排放。

褶曲翼部区煤层倾角变化诱发冲击地压机理及其防治研究

以宝积山煤矿七采区内褶曲翼部影响区为工程地质背景,采用现场调研统计、理论计算分析、数值模拟运算等方法,对开采煤层倾角变化诱冲机理进行研究,提出协同控制防治冲击地压方案并进行了现场工业性试验。结果表明:随着煤层倾角增大,煤柱侧内高集中静载呈现出逐渐增大的规律,实体煤侧内高集中静载呈现出逐渐减小的规律;在煤层倾角较小的条件下,厚硬关键层更容易在采空区两侧边界位置发生破断,诱使其悬空段中部区域瞬间发生破断进而形成扰动强度较大的远场应力扰动;关键块体B在煤层倾角较小且埋深较大的条件下极易发生回转失稳,进而形成扰动强度较小的近场应力扰动。该方法对于冲击地压的防治效果显著。

基于Duncan-Chang模型的地基沉降分层总和分析方法探讨

地基沉降分析方法是土力学研究的重要内容。该文在地基沉降变形力学机理研究基础上,首先考虑埋深或初始地应力即先期固结应力对地基土变形模量的影响,并将其区分为初始地应力的体积应力和偏应力影响两部分,引进分级加载思想,建立出不同埋深地基土变形模量的确定方法;其次,将地基沉降区分为附加体积应力和附加偏应力引起的沉降两部分,建立出地基沉降分析计算模型;然后,考虑地基变形的非线性变化特征,引进增量分析方法、虎克定律和Duncan-Chang模型,建立出附加体积应力和附加偏应力引起的地基压缩层变形的分析方法,并利用地基沉降分层总和法分析原理,建立出基于Duncan-Chang模型的地基沉降分析新方法。该方法不仅可以反映初始地应力和附加应力对地基土变形模量的影响,而且,可避免地基土压缩试验曲线和地基静载试验曲线的使用;最后,通过工程实例计算与分析,并与实测沉降值和现有分析方法的计算结果进行比较,表明了该方法可以满足工程计算精度要求,具有一定的合理性与可行性。

酿酒葡萄“厂”形四步整形技术及应用效果调查

西北地区的葡萄栽培中,秋季的埋土防寒是必要环节,因此适宜的整形技术是保证葡萄酒产业可持续发展的重要措施。文章以‘赤霞珠’和‘马瑟兰’等主要酿酒品种为对象,根据多年实践经验总结出了“厂”形的四步整形技术:一年培育壮苗,二年培育壮蔓,三年上架结果,四年基本成形。通过调查各品种幼龄树的生长发育情况发现,栽植第一年多数品种的新梢在秋季的成熟芽眼数达到10个以上,但第二年‘赤霞珠’‘美乐’‘马瑟兰’3品种的长势较好,其它品种长势较差;对产量和品质的调查发现,各品种四年生树的产量较低,并以‘赤霞珠’和‘马瑟兰’品种表现较好,分别达到十年生树的78.19%和68.65%;而果实品质与十年生树无明显差异。综上所述,“厂”形树形适用于西北埋土防寒区酿酒葡萄栽培。

基于STEP与XML的虚拟企业制造信息共享及信息安全研究

在对虚拟企业制造信息的集成框架进行分析的基础上,本文研究了基于XML与STEP如何实现虚拟企业制造信息共享及信息安全问题,讨论了从STEP到XML的转换和XML安全技术。最后,举例说明了虚拟企业制造信息集成的实现。