多级延时消去滤波电压频率实时检测方法

实时检测电网电压频率是电力系统控制与保护的前提,然而在非理想三相电网电压情况下,频率检测存在速度慢、精度低等问题。为此,提出一种多级延时消去滤波数字信号处理技术,在两相αβ静止坐标系下,分离出正交、平衡的基波正序电压成分。进而将两相电压信号进行幅值归一化,结合微分与开方运算,实时检测各种电能质量情况下三相电压的频率信息。详细比较了多级延时消去滤波的衰减特性及动态响应时间,数值仿真与基于数字信号处理器的实验测试结果验证了所提方法的正确性和可行性。该方法适应性强、运算量少、响应速度基本固定,最大稳态检测误差不超过0.05 Hz,适合嵌入式平台实现。

雷达动目标显示模拟系统

运用数字电路建立了雷达动目标显示模拟系统 ,并对其设计原理进行了分析说明 ,给出了对消运算的回波信号波形及运算规则。该系统简便经济 。

Effect of Disinfection Time on Microbial Content and Quality of Cold Fresh Chicken

[Objective] The aim was to provide reference for the production technolo- gy of cold fresh chicken. [Method] Lactic acid was used as the disinfectant in cooling water, so as to study the effect of disinfection time on the microbial content and quality of cold fresh chicken. [Result] With disinfection of 20 min, the removal rates of the total colonies, coliforms and moulds reached over 95%. As the disinfec- tion time was further extended, it had no significant effect on the removal effects of the microbial content and could affect the tenderness and color of cold fresh chick- en. [Cendusion] The study provides references for the design and optimization of the production process of cold fresh chicken.

基于CPLD技术的多参数自适应测试系统设计

利用CPLD(ComplexProgrammableLogicDevice)研究设计了用于炮弹多参数测试系统。该研究选用xilinx公司的最新产品coolrunnercpld系列可编程器件。详细介绍了cpld的性能、系统的组成、工作原理和测试系统电路框图,并研究了其低功耗的实现。

不同助排方式改善蒸汽吞吐效果实验及数值模拟

由于稠油油藏的蒸汽吞吐开发属于降压式衰竭开采,导致吞吐后期油藏能量不足,蒸汽超覆严重,垂向扫油系数低,开采效果变差。注蒸汽的同时伴注一定量的气体及化学剂辅助蒸汽吞吐可改善流度比,有效改善稠油油藏的开发效果。利用室内单管实验研究了不同助排方式对蒸汽吞吐效果的影响,实验结果表明,与无助排相比,烟道气泡沫助排驱油效率可提高19%。在此基础上,利用数值模拟方法对比多种助排方式对蒸汽吞吐效果的影响,其结果与物理模拟实验结果吻合。综合多方面因素,烟道气泡沫助排效果最佳,其次为氮气泡沫助排,尤其是当地层的非均质性差以及原油粘度较高时,烟道气泡沫辅助蒸汽吞吐的开发效果更为明显。

Estimating model for urban carrying capacity on bike-sharing

As the demand for bike-sharing has been increasing,the oversupply problem of bike-sharing has occurred,which leads to the waste of resources and disturbance of the urban environment.In order to regulate the supply volume of bike-sharing reasonably,an estimating model was proposed to quantify the urban carrying capacity(UCC)for bike-sharing through the demand data.In this way,the maximum supply volume of bike-sharing that a city can accommodate can be obtained.The UCC on bike-sharing is reflected in the road network carrying capacity(RNCC)and parking facilities’carrying capacity(PFCC).The space-time consumption method and density-based spatial clustering of application with noise(DBSCAN)algorithm were used to explore the RNCC and PFCC for bike-sharing.Combined with the users’demand,the urban load ratio on bike-sharing can be evaluated to judge whether the UCC can meet users’demand,so that the supply volume of bike-sharing and distribution of the related facilities can be adjusted accordingly.The application of the model was carried out by estimating the UCC and load ratio of each traffic analysis zone in Nanjing,China.Compared with the field survey data,the effect of the proposed algorithm was verified.

Determination of Hf–Sr–Nd isotopic ratios by MC-ICP-MS using rapid acid digestion after flux-free fusion in geological materials

In this study, we established a rapid acid digestion for determining Hf-Sr-Nd isotopic ratios of geological samples by using MC-ICP-MS. Conditions of 1600 ℃ for 1 min and 1400 ℃ for 1 min were adopted for fusing intrusive rocks and extrusive rocks, respectively. The rapid acid digestion technique is superior in digestion time compared with high-pressure PTFE bomb method. The procedural blanks of the method were also lower than that flux fusion. Replicate analyses of international certified reference materials （CRMs） indicate that isotopic ratios of ^176Hf/^177Hf, ^87Sr/^86Sr and 143Nd/144Nd agree well with previously published data. The external reproducibility （2SD, n = 5） of ten CRMs are ±0.000030 for ^87Sr/^86Sr, ± 0.000030 for ^143Nd/^144Nd, and ±0.000018 for ^176Hf/^177Hf.

Lagrangian model of zooplankton dispersion:numerical schemes comparisons and parameter sensitivity tests

This paper presents two comparisons or tests for a Lagrangian model of zooplankton dispersion:numerical schemes and time steps.Firstly,we compared three numerical schemes using idealized circulations.Results show that the precisions of the advanced Adams-Bashfold-Moulton(ABM) method and the Runge-Kutta(RK) method were in the same order and both were much higher than that of the Euler method.Furthermore,the advanced ABM method is more efficient than the RK method in computational memory requirements and time consumption.We therefore chose the advanced ABM method as the Lagrangian particle-tracking algorithm.Secondly,we performed a sensitivity test for time steps,using outputs of the hydrodynamic model,Symphonie.Results show that the time step choices depend on the fluid response time that is related to the spatial resolution of velocity fields.The method introduced by Oliveira et al.in 2002 is suitable for choosing time steps of Lagrangian particle-tracking models,at least when only considering advection.

Effect analysis of friction and damping on anti-backlash gear based on dynamics model with time-varying mesh stiffness

A nonlinear model of anti-backlash gear with time-varying friction and mesh stiffness was proposed for the further study on dynamic characteristics of anti-backlash gear. In order to improve the model precision, applied force analysis was completed in detail, and single or double tooth meshing states of two gear pairs at any timing were determined according to the meshing characteristic of anti-backlash gear. The influences of friction and variations of damping ratio on dynamic transmission error were analyzed finally by numerical calculation and the results show that anti-backlash gear can increase the composite mesh stiffness comparing with the mesh stiffness of the normal gear pair. At the pitch points where the frictions change their signs, additional impulsive effects are observed. The width of impulsive in the same value of center frequency is wider than that without friction, and the amplitude is lower. When gear pairs mesh in and out, damping can reduce the vibration and impact.

A Distributed 2D-to-3D Video Conversion System

2D-to-3D video conversion is a feasible way to generate 3D programs for the current 3DTV industry. However, for large-scale 3D video production, current systems are no longer adequate in terms of the time and labor required for conversion. In this paper, we introduce a distributed 2D-to-3D video conversion system that includes a 2D-to-3D video conversion module, architecture of the parallel computation on the cloud, and 3D video coding in the system. The system enables cooperation among multiple users in the simultaneous completion of their conversion tasks so that the conversion efficiency is greatly promoted. In the experiments, we evaluate the system based on criteria related to both time consumption and video coding performance.

Data Distribution Mechanism over Opportunistic Networks with Limited Epidemic

Most of data distribution mechanism in Opportunistic Networks is derived by Epidemic data distribution,and Epidemic data distribution means that when each node meets another node,it may copy its own messages and transfer to another node.On the one hand,the copies improve the forwarding rate,and reduce the transmission delay.However,on the other hand,energy consumption increases and network survival time is reduced because the copies consume transmission resource.Therefore,copy number should be under control.In this paper,we first introduce the existing routing strategy based on Epidemic briefly,and present the Epidemic routing protocol analysis model and copy control mechanism based on the limited Epidemic in Opportunistic Networks.Then based on the limited copies scheme(LCS),we propose an energy balance scheme(EBS),the results show that EBS can improve the network survival time.

The role of physical activity and exercise in obesity and weight management: Time for critical appraisal

The prevalence of overweight and obesity has increased dramatically during last 3 decades with devastating consequences to public health. Recommended strategies to reduce obesity have focused on healthier diet and physical activity （PA）. Clearly, these approaches have not been successful, but whether this is due to failure to restrict energy intake or to maintain high levels of energy expenditure has been the subject of great controversy. Consequently, there has been a great deal of confusion about the role of PA and exercise in obesity and weight management. In this article, the theoretical basis for considering reduced PA and energy expenditure as the cause of obesity is appraised. Further, the role of PA in food intake and weight control is examined. The idea that obesity is caused by consistent deeline in daily energy expenditure is not supported either by objective measures of energy expenditure or physiological theory of weight gain alone. However, since voluntary exercise is the most important discretionary component of total daily energy expenditure, it can affect energy balance. Therefore, PA and exercise hold potential as part of the solution for the ongoing obesity epidemic.

Operating performance of novel reverse-cycle defrosting method based on thermal energy storage for air source heat pump

To solve the fundamental problem of insufficient heat available during defrosting while ensuring the efficient and safe system operation for air-source heat pumps (ASHPs). A novel reverse-cycle defrosting (NRCD) method based on thermal energy storage to eliminate frost off the outdoor coil surface was developed. Comparative experiments using both the stand reverse cycle defrosting (SRCD) method and the NRCD method were carried out on an experimental ASHP unit with a nominal 2.5 kW heating capacity. The results indicate that during defrosting operation, using the NRCD method improves discharge and suction pressures by 0.24 MPa and 0.19 MPa, respectively, shortens defrosting duration by 60%, and reduces the defrosting energy consumption by 48.1% in the experimental environment, compared with those by the use of SRCD method. Therefore, using the NRCD method can shorten the defrosting duration, improve the indoor thermal comfort, and reduce the defrosting energy consumption in defrosting.

The effect of simulated gastrointestinal digestion on shrimp Penaeus vannamei allergenicity

Pen a 1 is a major shrimp allergen that induces an allergy. The aim of this study is to assess the effect of simulated gastrointestinal fluids on the allergenicity of Pen a 1. Purified Pen a 1 from shrimp （Penaeus vannamei） was subjected to digestion in SGF （simulated gastric fluid） and SIF （simulated intestinal fluid） for a set time. The allergenicity of digestive Pen a 1 was analyzed by immunoblotting and Ci-ELISA, using pool sera from patients with shrimp specific IgE. The results showed that Pen a 1 exhibited a decrease in allergenicity with increasing digestion time in the SGF and SIF. However, Pen a 1 exhibited strong resistance to digestive fluids, and all yielded fragments （33 kD, 23 kD, and 14 kD） showed allergic activity. Therefore, anti-digestion may be an important factor for Pen a 1 to induce an allergy.

Bacterial flora concurrent with Helicobacter pylori in the stomach of patients with upper gastrointestinal diseases

AIM： To investigate the non-He/icobacterpy/ori （H. pylori） bacterial flora concurrent with H. pylori infection.METHODS： A total of 103 gastric biopsy specimens from H. pylori positive patients were selected for bacterial culture. All the non-H, pylori bacterial isolates were identified by matrix assisted laser desorption ionization time-of-flight mass spectrometry （MALDI-TOF MS）.RESULTS： A total of 201 non-H, pyiori bacterial isolates were cultivated from 67 （65.0%） of the 103 gastric samples, including 153 isolates identified successfully at species level and 48 at genus level by MALDI-TOF MS. The dominant species were Streptococcus, Neisseria, Rothla and Staphylococcus, which differed fromthe predominantly acid resistant species reported previously in healthy volunteers. The prevalence of non-H. pylori bacteria was higher in non-ulcer dyspepsia group than in gastric ulcer group （100% vs 42.9%, P 〈 0.001）. Six bacterial species with urease activity （Staphylococcus epidermidis, Staphylococcus warneri, Staphylococcus capitis, Staphylococcus aureus, Brevibacteriurn spp. and Klebsiella pneumoniae） were also isolated.CONCLUSION： There is a high prevalence of the non-H, pylori bacteria concurrent with H. pylori infection, and the non-H, pylori bacteria may also play important as-yet-undiscovered roles in the pathogenesis of stomach disorders.

Nearest Object Priority Based Integrated Rough Surface Scattering Algorithm for 3D Indoor Propagation Prediction

Since rough surface scattering has a great impact on the accuracy of the propagation prediction algorithm,an integrated algorithm for indoor propagation prediction including rough surface scattering is proposed here.This algorithm is composed of a three dimensional(3D) ray tracing algorithm based on binary space partitioning(BSP) and a diffuse scattering algorithm based on Oren-Nayar's theory.Lack of accuracy and prohibitive time consumption are the main drawbacks of the existing ray tracing based propagation prediction models.To defy these shortcomings,the balanced BSP tree is used in the proposed algorithm to accelerate the ray tracing,while the nearest object priority technique(NOP) and in contact surface(ICS) is used to eliminate the repeated rayobject intersection tests.Therefore,the final criteria of this study are the time consumption as well as accuracy by predicting the field strength and the number of received signals.Using the proposed approaches,our algorithm becomes faster and more accurate than the existing algorithms.A detailed comparative study with existing algorithms shows that the proposed algorithm has at most 37.83%higher accuracy and 34.44%lower time consumption.Moreover,effects of NOP and ICS techniques and scattering factor on time and ray prediction accuracy are also presented.

Role of surgical intervention in managing gastrointestinal metastases from lung cancer

AIM:To investigate the clinicopathological characteristics of late-stage lung cancer patients with gastrointestinal(GI)-tract metastases,focusing on therapeutic options and outcomes.METHODS:Our institution(the National Taiwan University Hospital) diagnosed 8159 patients with lung cancer between 1987 and 2008,of which 21 developed symptomatic GI metastases.This study reviewed all of the patients' information,including survival data,pathological reports,and surgical notes.RESULTS:The most common histological type of lung cancer was adenocarcinoma,and 0.26% of patients with lung cancer developed GI metastases.The median duration from lung cancer diagnosis to GI metastases was three months(range,0-108 mo),and the average time from diagnosis of GI metastasis to death was 2.8 mo.Most patients with symptomatic gastric and/or duodenal metastases exhibited GI bleeding and were diagnosed by panendoscopy.In contrast,small bowel metastases typically presented as an acute abdomen and were not diagnosed until laparotomy.All patients with small bowel or colonic metastases underwent surgical intervention,and their perioperative mortality was 22%.Our data revealed a therapeutic effect in patients with solitary GI metastasis and a favorable palliative effect on survival when metastases were diagnosed preoperatively.In patients with multiple GI metastases,the presentation varied according to the locations of the metastases.CONCLUSION:Surgical treatment is worthwhile in a select group of patients with bowel perforation or obstruction.Physicians should be more alert to symptoms or signs indicating GI metastases.

Personalized Management of Anastomotic Leak after Surgery for Esophageal Carcinoma

Objective To summarize the management of anastomotic leak following surgery for esophageal car-cinoma. Methods The medical records of the patients developing digestive tract leak after surgery for esophageal carcinoma in our hospital from January 2003 to March 2011 were retrospectively analyzed. Results A total of 36 patients were included, in whom 13 developed cervical anastomotic leak, 18 had intra-thoracic anastomotic leak, and 5 had intra-thoracic gastric necrosis. Of these patients, 7 were treated with resurgery, 6 with esophageal stent implantation, and 23 with conservative treatment. Treatment lasted for 5 to 181 days, averagely 47.0±31.9 days. After management, 9 patients died (25.0%). Among seven patients with resurgery, four had deceased, two were cured, and one developed leak again and was switched to conservative treatment until discharged. All the 6 patients treated with stent implantation were cured. Of the 24 patients receiving conservative treatment (including one switched from resurgery), 18 (75.0%) were cured and 1 was not cured but survived. Conclusions Anastomotic leak following surgery for esophageal carcinoma should be treated individually based on the onset time, location, size, and extent of the leakage. Conservative treatment is still a safe and effective method.The efficacy of stent implantation needs further investigation to confirm.

4-D Trajectory Prediction and Dynamic Planning of Aircraft Taxiing Considering Time and Fuel

Most of the traditional taxi path planning studies assume that the aircraft is in uniform speed,and the optimization goal is the shortest taxi time.Although it is easy to solve,it does not consider the changes in the speed profile of the aircraft when turning,and the shortest taxi time does not necessarily bring the best taxi fuel consumption.In this paper,the number of turns is considered,and the improved A*algorithm is used to obtain the P static paths with the shortest sum of the straight-line distance and the turning distance of the aircraft as the feasible taxi paths.By balancing taxi time and fuel consumption,a set of Pareto optimal speed profiles are generated for each preselected path to predict the 4-D trajectory of the aircraft.Based on the 4-D trajectory prediction results,the conflict by the occupied time window in the taxiing area is detected.For the conflict aircraft,based on the priority comparison,the waiting or changing path is selected to solve the taxiing conflict.Finally,the conflict free aircraft taxiing path is generated and the area occupation time window on the path is updated.The experimental results show that the total taxi distance and turn time of the aircraft are reduced,and the fuel consumption is reduced.The proposed method has high practical application value and is expected to be applied in real-time air traffic control decision-making in the future.

Sorafenib in hepatocellular carcinoma:efficacy and predictive factors

Objective:To evaluate the efficacy and safety in patients with hepatocellular carcinoma treated with sorafenib and determine the predictive factors for survival.Methods:From April 2009 to December 2010,all patients with hepatocellular carcinoma treated with sorafenib were included in the study.Clinical data and survival time were collected.Survival analysis was conducted using the Kaplan-Meier method,and predictive factors for survival were analysed using the Cox's model.Results:A total of 51 patients were included in the study,the median time of follow-up was 10 months(range 1-22).All the 51 patients had one or more adverse events,of which 2 patients died of upper gastrointestinal bleeding and 6 patients discontinued treatment.The mean survival time was 11 months and 1-year survival was 60.8%.On univariate analysis,the median survival time of patients with tumors of BCLC A,B and C were 17,12.5 and 8.5 months,and 1-year survival were 71.4%,61.1%,and 23.1%, respectively(P=0.006).Compared with those with mild and poor arterial supply tumors,patients with good arterial supply tumors had longer median survival time(12 months vs 8 months and 9 months) and higher 1-year survival(52.0%vs 30.8%and 38.5%)(P=0.037).Patients with portal invasion had shorter median survival time and lower 1-year survival(8.5 months vs 13 months and 57.6%vs 16.7%,respectively) than those without(P=0.012).Patients with prealbumin≥170 mg/L had longer median survival time and higher 1-year survival(13.5 months vs 9 months and 55.6%vs 36.4%,respectively) than those with prealbumin<170 mg/L(P=0.016).Early tumor BCLC staging and high level of prealbumin were independent predictive factors for survival on multivariate analysis using Cox's regression model,the hazard ratio were 3.69(95%CI:1.30-10.53,P=0.015) and 3.53(95%CI:1.40-8.91,P=0.008) respectively.Conclusion:Upper gastrointestinal bleeding was a severe event need to be concerned in patients with hepatocellular carcinoma treated with sorafenib.Patients with high level of prealbumin could benefit more from sorafenib treatment,and prealbumin could be a predictor for survival in HCC patients treated with sorafenib.