无人机系统视距链路全断故障分析与改进

无人机曾发生UHF上、下行链路和C链路陆续中断,全程持续约20 min。从视距链路系统功能原理出发,定位故障原因,分析故障机理,确定中断原因分别为区域内存在干扰信号、任务管理处理机中OFP软件存在缺陷和应急处置错误选择了定向天线的伺服方式。最后采取了针对性改进措施,彻底解决了视距链路主备全断故障。该故障解决进一步完善了应急处置体系,对于预防危险性故障,提高系统整体可靠性具有重要意义。

全断面掘进机在煤矿工作实践中的安全要求

随着现代工业发展进程加快,煤炭能源消耗量与日俱增,煤炭应用范围广阔,开采煤炭资源会释放大量废气,对环境造成污染,同时可能破坏地表结构,污染地下水资源。因此控制煤炭资源开采的安全、环保是煤矿开采行业急需解决的问题。可通过更新施工开采方案、增加新施工机械设备来达到这一目标,改善煤矿开采对环境造成的影响,使用全断面掘进机能够有效缓解污染问题。

自动化走航式全断面积宽法悬移质输沙率测验研究

传统的悬移质输沙率人工测验方式耗时耗力,效率低下。论述了在南宁水文站开展自动化走航式全断面积宽法悬移质输沙率测验的研究过程和方法,通过对应浊度试验传感器悬移质断面平均含沙量的比测,建立新的断沙关系模型;通过对浊度传感器悬移质单样含沙量的比测,建立新的单断沙关系模型。从而实现测流测沙一体化,达到悬移质输沙率自动监测的目的。

自动化走航式全断面积宽法悬移质输沙率测验关键技术的研究

传统悬移质输沙率测验为人工测验方式,耗时耗力、效率低下。由于低效率测验方式的泥沙信息不能满足经济社会发展的需求,只有改革悬移质泥沙测验方式,才能实现悬移质输沙率测验自动化。在南宁水文站开展自动化走航式全断面积宽法悬移质输沙率测验关键技术的研究,根据浊度与悬移质泥沙的相应关系建立模型,将悬移质输沙率测验的含沙量监测,通过由浊度监测转为泥沙监测,达到悬移质输沙率测验自动化的目的。

多天线频谱共享CR-NOMA系统安全中断性能分析

认知无线电(CR)非正交多址接入(NOMA)网络(记为CR-NOMA)已是无线通信领域的研究热点之一。由于无线信道的开放性,使得无线网络的安全通信成为当前急需解决的问题。该文研究了频谱共享多天线CR-NOMA网络安全中断性能,首先分析了最优天线选择(OAS)方案的安全中断概率(SOP),并推导了其精确的闭合表达式。其次,分析了空时传输(STT)方案的SOP,并推导了其精确的闭合表达式。最后,对次用户两种方案的SOP渐近性能进行了分析,揭示了系统参数对SOP的影响。最后,采用Monte Carlo仿真验证了理论分析的正确性。研究发现,两种方案基站分别存在一个最优峰值发射功率,使得远距离次用户的安全中断性能最佳。仿真结果表明增大基站峰值发射功率,OAS方案的近距离次用户的SOP会始终优于STT方案,远距离次用户的SOP会劣于STT方案。

成功修复断指(趾)

近2a来笔者收治了8例指、趾几乎完全断离,既无法承受再植经费,又不愿剪除指、趾的病人,经清创,缝合及抗炎、解除血管痉挛、促血管再生等治疗,均成功愈合。现报告如下:

喷彩而出

“Epson/Photo EX是目前为止唯一具有A3幅面Macintosh串行接口的喷墨打印机,如果是A3幅面的图片,720DPI打印,只需8分钟;若是1440DPI打印,则需要14分钟。”商家给出这些解释,目的是想强调它价格的合理性,3350元的销价。

Design and Study of a High Security ATM System

Based on the characteristics of ATM system and the special requirement of financial transaction, an overall design of hardware and software structure of ATM was made. For software structure, the pattern of modules and table? drive is adopted to realize the security of financial transaction and the diagnosis of communication fault. A new method, which is based on the application layer, transport layer and network layer, is used for diagnosing communication fault. Supporting both magnetic card and IC card, the system has been put into use in real financial systems, and has brought about both economic and social effects.

Optimal design for buckets layout based on muck removal analysis of TBM cutterhead

The layout of the buckets for tunnel boring machine(TBM)directly affects the muck removal efficiency of cutterhead during excavation.In order to improve the muck removal performance for TBM,the optimal design of bucket layout was investigated.The whole muck transfer process was simulated by discrete-element method(DEM),including the muck falling,colliding,pilling up,shoveling and transferring into the hopper.The muck model was established based on size distribution analysis of muck samples from the water-supply tunnel project in Jilin Province,China.Then,the influence of the bucket number and the interval angle between buckets on muck removal performance was investigated.The results indicated that,as the number of buckets increased from four to eight,the removed muck increased by 29%and the residual volume decreased by 40.5%,and the process became steadier.Different interval angles between buckets were corresponding to different removed muck irregularly,but the residual muck number increased generally with the angles.The optimal layout of buckets for the cutterhead in this tunnel project was obtained based on the simulation results,and the muck removal performance of the TBM was verified by the actual data in the engineering construction.

Holocene activity evidence on the southeast boundary fault of Heqing basin, middle segment of Heqing-Eryuan fault zone, West Yunnan Province, China

The Heqing-Eryuan fault is an important part of the active fault system in the Northwestern Yunnan Province, China. Thus, the study on the nature, characteristics and activity history of this fault can provide not only the basis for seismic safety and engineering evaluation, but also the important information for the characteristics, history and patterns of the structural deformation of the southeastern margin of the Tibetan Plateau. Trench and faulted landforms investigations could provide effective paleoseismic methods to obtain the recent parameters of active faults. Using these methods, this study makes some breakthroughs on the recent activity of southeast boundary fault of the Heqing basin, middle segment of Heqing-Eryuan fault zone. Results indicate that the average vertical slip rate and left-lateral slip rate of the segment are about 0.28 mm/a and 1.8o mm/a respectively since the Late Pleistocene. The trench near the Beixi Village at the .outhea.t houndnrv fault of the lqaaing basinreveals that there have been at least three paleoearthquake events during the Holocene （8 ka BP）. The vertical displacement and sinistral strike-slip distance of a single paleoearthquake are ~20 cm and -1.2 m, respectively. The estimated paleoearthquake magnitudes with Ms7.o, and the recurrence interval at 2-5 ka, as well as the latest activity time during 800- 290 ca1 yr BP, are of great significance for preventing and mitigating regional earthquake disasters.

Late Pleistocene-Holocene slip history of the Langshan-Seertengshan piedmont fault(Inner Mongolia,northern China) from cosmogenic ^(10)Be dating on a bedrock fault scarp

Offset geomorphic features and deformed late Quaternary strata indicate active deformation along the Langshan-Seertengshan piedmont fault （LSPF）, one of the most active faults in the Hetao fault zone in Inner Mongolia, North China. The widespread occurrence of bedrock fault scarps along the LSPF offers excellent opportunity to examine the faulting history. Using cosmogenic ^10Be exposure dating, we measured the exposure ages of the western Langshankou scarp, located in the middle segment of the LSPF. Our data revealed at least two earthquakes that occurred at 22.2±3.3 Ira and 7.2±2.4 ka, respectively. These events are consistent with previous paleoseismic trench studies. The regression of the relationship between the age and sampling height along the scarp yield a fault slip rate of 0.10 ±0.05/-0.06 mm/yr, which is significantly lower than the average post-late Pleistocene fault slip rate of ~1 mm/yr, as estimated from the offset of the T2 terraces by previous studies. This indicates that the slip of the LSPF may have been accommodated by other fault branches.

Safety diagnosis on coal mine production system based on fuzzy logic inference

According to the randomness and uncertainty of information in the safety diagnosis of coal mine production system (CMPS), a novel safety diagnosis method was proposed by applying fuzzy logic inference method, which consists of safety diagnosis fuzzifier, defuzzifier, fuzzy rules base and inference engine. Through the safety diagnosis on coal mine roadway rail transportation system, the result shows that the unsafe probability is about 0.5 influenced by no speed reduction and over quick turnout on roadway, which is the most possible reason leading to the accident of roadway rail transportation system.

The Analysis of Secure HARQ with Chase Combining over Block Fading Channel

In this letter, the physical layer security of hybrid automatic repeat request with chase combining(HARQ-CC) scheme is investigated from the viewpoint of information theory. Different from the literature which used Wyner code, our analysis focuses on the general scenario without specific code. We firstly obtain the outage probability of both main channel and wiretap channel. Since retransmissions are completely determined by main channel, we then prove that its achievable diversity order equals to maximum transmission number() while this order of wiretap channel is only one. Furthermore, we evaluate the metric of secure gap which demonstrates the difference between main channel and wiretap channel with reliable and secure constraints. As increases, the secure gap decreases monotonously. When is large enough, the security can be guaranteed even if wiretap channel is better than main channel.

Appropriateness of colonoscopy: Diagnostic yield and safety in guidelines

AIM: To evaluate if the guidelines for the appro-priateness of performing colonoscopy by American Society for Gastrointestinal Endoscopy (AGSE) and Italian Society of Digestive Endoscopy (SIED) yield a good diagnostic efficacy and do not present risks of missing important colonic pathologies in an Italian population sample.METHODS: A total of 1017 consecutive patients (560 men and 457 women; mean age 64.4 ± 16 years) referred to an open-access endoscopy unit for colonoscopy from July 2004 to May 2006 were evaluated according to ASGE and SIED guidelines for appropriateness of performing the procedure. Diagnostic yield was defined as the percentage of relevant colonic pathologies of the total number of colonoscopies performed.RESULTS: About 85.2% patients underwent colono-scopy that was considered appropriate based on at least one ASGE or SIED criterion, while it was considered inappropriate for 14.8% of patients. The diagnostic yield of colonoscopy was significantly higher for appropriate colonoscopies (26.94% vs 10.6%, P < 0.001) than for inappropriate colonoscopies (5.3%). There was no missed colorectal cancer following the ASGE/SIED criteria.CONCLUSION: ASGE/SIED guidelines have shown a good diagnostic yield and the rate of missing relevant colonic pathologies seems very low. Unfortunately, the percentage of inappropriate referrals for colonoscopy in an open-access endoscopy system is still high, despite the number of papers published on the issue and the definition of international guidelines. Further steps are required to update and standardize the guidelines to increase their diffusion and to promote educational programs for general practitioners.

Coordination and nursing care of pediatric patients undergoing double balloon enteroscopy

AIM:To review safety,efficacy,and proper nursing care of double-balloon enteroscopy (DBE) in pediatric patients with small intestinal disease.METHODS:Our study included 37 patients with abdominal pain,diarrhea,passage of blood in the stools,and other symptoms,who underwent DBE from December 2006 to July 2010.DBE was retrograde in 36 procedures,antegrade in six,and from both ends in five.The diagnostic significance and salient points in nursing care are discussed in this article.RESULTS:At least one lesion was discovered in 28 out of 37 patients,which yielded a positive diagnosis in 75.7% of cases.Good bowel preparation and skilled nursing care not only shortened the procedure time,but could also alleviate patient discomfort and enhance the quality of examination.No serious procedure-related complications were observed in any cases.CONCLUSION:DBE is a new modality of endoscopic procedure that improves the standard of diagnosis and treatment of small bowel diseases in children.Good nursing care is essential to the successful execution of the procedure.

The research of breakdown structure and coding system for construction project

Whether the breakdown structure and coding system of construction projects are reasonable or not determines to a large degree the performance level of the entire project management. We analyze in detail the similarities and differences of two kinds of decomposing methods classified by type of work and construction elements based on the discussion of international typical coding standards system designing. We then deduce the differential coefficient relation between project breakdown structure (PBS) and work breakdown structure (WBS). At the same time we constitute a comprehensive construction project breakdown system including element code and type of work code and make a further schematic presentation of the implementation of the system’s functions.

GiT-based structural geologic feature analysis of the southern segment of Longmenshan fault zone for earthquake evidence

The Longmenshan fault is a thrust fault which runs along the base of the Longmen Mountains in Siehuan province, southwestern China. The southern segment of the fault had two distinct responses to the Ms 8 Wenehuan and Ms 7 Lushan earthquakes. This study determines characteristics of the structural geology of the Longmenshan fault to evaluate how it influenced the two aforementioned earthquakes. This research was done within a Geo- information Technologies （GiT） environment based on multi-source remote sensing and crustal movement data extracted from the Global Positioning System （GPS）. The spatial distribution of the southern segment of the Longmenshan fault zone was comprehensively analyzed to study both earthquakes. The study revealed that the Wenehuan and Lushan earthquakes occurred on two relatively independent faults. In addition, there was a nearly constant-velocity crustal movement zone between the two epicenters that probably had a compressive stress with slow motion. Furthermore, the central fault and a mountain back fault gradually merged from north to south. The Lushan earthquake of the Wenchuan earthquake. was not an affershock The research showed that fault zones within 30-50 km of State Highway 318 are intensive and complex. In addition, crustal movement velocity decreased rapidly, with a strong multi-directional shear zone. Thus, activity in that zone was likely stronger than in the northern part over the medium to long term.

Statistical analysis of fracture properties based on particle swarm optimization and Pearson correlation coefficient method

Prediction of reservoir fracture is the key to explore fracture-type reservoir. When a shear-wave propagates in anisotropic media containing fracture,it splits into two polarized shear waves: fast shear wave and slow shear wave. The polarization and time delay of the fast and slow shear wave can be used to predict the azimuth and density of fracture. The current identification method of fracture azimuth and fracture density is cross-correlation method. It is assumed that fast and slow shear waves were symmetrical wavelets after completely separating,and use the most similar characteristics of wavelets to identify fracture azimuth and density,but in the experiment the identification is poor in accuracy. Pearson correlation coefficient method is one of the methods for separating the fast wave and slow wave. This method is faster in calculating speed and better in noise immunity and resolution compared with the traditional cross-correlation method. Pearson correlation coefficient method is a non-linear problem,particle swarm optimization( PSO) is a good nonlinear global optimization method which converges fast and is easy to implement. In this study,PSO is combined with the Pearson correlation coefficient method to achieve identifying fracture property and improve the computational efficiency.