Analysis the Results of Control and Elimination of Coal-Burning-Borne Endemic Fluorosis in Chongqing City

Objective: Discuss the analysis of the results of control and elimination of coal-burning fluorosis in Chongqing, and evaluate the effect of prevention and control. Methods: Dean’s method was used to investigate the fluorosis for the local children whose ages ranged from 8 to 12 years old, the use of improved stoves in residential households, the drying of corn and pepper for human consumption, and the results were evaluated and discussed according to the national standard for the control and elimination of coal-burning fluorosis. Results: The prevalence rate of dental fluorosis borne-disease in children whose ages ranged from 8 to 12 years old was about 11.28% in 661 historically diseased villages in 100 townships and in 13 districts and counties of Chongqing city. The correct utilization rates of improved stoves, qualified improved stoves, and qualified stoves were 100%, 98.82%, and 99.45%, respectively. The correct drying rates of corn and pepper for human consumption were 99.88% and 99.75% respectively. There are 24 uncontrolled villages, 225 controlled villages, and 412 villages in eliminated disease zones in administrative villages. There are 4 villages and counties in uncontrolled, 4 in controlled, and 5 eliminated areas in districts and counties. Conclusion: Fluorosis borne-disease caused by coal-burning in Chongqing has reached the control and elimination targets of the twelfth Five-year plan.

A type of inverter power supply based on harmonic elimination PWM control

In order to output sine wave with small degree of distortion and improve stability,a type of inverter power supply is designed based on harmonic elimination pulse-width modulation(PWM)control.The rectifier and filter are added to input circuit of the inverter.Single-phrase full-bridge inverter performs the function of converting direct current into alternating current(DC/AC).In the control circuit,single chip micyoco(SCM)AT89C2051 is used for main control chip to accomplish the hardware design of the control system.A given value of output frequency of the inverter is input in the way of coding.According to the output frequency code which is read,SCM AT89C2051 defined harmonic elimination PWM control data which will be selected.Through internal timing control,the switches are switched under this provision of PWM control data.Then the driving signals of the switches in the inverter are output from I/O of SCM AT89C2051 to realize harmonic elimination PWM control.The results show that adding Newton homotopic algorithm of harmonic elimination PWM control to corresponding software of the control system can make the quality of output voltage of the inverter higher and it will have broad application prospects.

The Mechanism of Eliminating Harmonic Resonance with Controllers and Application to the Power Systems

The phenomenon of anti-symmetrical bifurcation of periodic solutionsoccurring near an integral manifold is the intrinsic cause resulting in harmonic resonanceover-voltage in power systems. Due to this discovery, the principle of eliminating resonance byusing anti-bifurcation technique is presented, which makes that the theoretical bases of verymeasure to eliminate resonance are unified firstly from a point of view of basic theory. Ourdiscussion models depend on a class of nonlinear control model. Using the direct Lyapunov method, acomplete theoretical proof is given in accordance with the measure of eliminating resonance byconnecting nonlinear resistor in series to the neutral point of P. T., and the feedback control lawbeing applied. It comprises the action of parameters of resistor to eliminate resonance and theactual process of eliminating resonance, i.e., to go against bifurcation process which forces thebig harmonic solutions to retreat to the integral manifold gradually and disappear eventually, whichby using the nonlinear controllers. This makes it sure that the intrinsic cause of resonance iseliminated thoroughly. The obtained theory results and computing results are better than thepresented results.

Setting up the Goal of Eliminating Outbreaks of Blue-green Alga, Innovating the Idea of Controlling the Taihu Lake, and Ensuring the Safety of Water Supply in the Taihu Lake

Since the water supply crisis in the Taihu Lake on May 29,2007,the control of the Taihu Lake has achieved remarkable results,and the eutrophication has been greatly reduced.Existing problems are as follows:outbreaks of blue-green alga still appear seriously every year,and there is no goal to eliminate outbreaks of blue-green alga;the load into the lake greatly exceeds the environmental capacity;reed wetlands are greatly reduced;there is still the possibility of a water supply crisis;the research of eliminating outbreak of blue-green alga is weak.In this paper,the experience of controlling the Taihu Lake is summarized,and the ultimate goals of eliminating eutrophication and outbreaks of blue-green alga and restoring wetlands and biodiversity are proposed.Control measures are proposed,such as deepening the promotion of the lake chief system,establishing the lake chief system in an all-round way,and increasing applied scientific and technological efforts and capital investment.The necessity and possibility of further controlling the Taihu Lake to eliminate outbreaks of blue-green alga should be recognized.Relying on controlling eutrophication alone cannot eliminate outbreaks of blue-green alga.The point that phosphorus control is the key to eliminate outbreaks of blue-green alga is not suitable for the Taihu Lake.The integration ideas of"three types"of technologies should be innovated.The first one is"double reduction and double increase"measures to eliminate eutrophication,of which"double reduction"is to reduce external point sources and non-point sources and internal blue-green alga in sediment;for external sources,the treatment standard of sewage plants should be paid special attention to.The second one is"double algae removal"measures to salvage blue-green alga,suppresses and kills algae.The blue-green alga on the surface,middle and bottom of water should be thoroughly salvaged and eliminated from various water areas.The third one is"double restoration"measures to restore wetlands and biodiversity.The area of wetlands should be restored to the area from the 1960s to the 1970s before outbreaks of blue-green alga,and vegetation coverage reaches 25%-30%.The Taihu Lake is controlled in different waters to ensure water supply safety in water sources.Five suggestions are proposed,such as revising the"Overall Plan for the Comprehensive Treatment of Water Environment in the Taihu Lake Basin"again,incorporating the goal of eliminating outbreaks of blue-green alga in the plan,setting up this research topic,greatly improving sewage treatment standards in local legislation.

Differential Correspondences and Control Theory

When a differential field K having n commuting derivations is given together with two finitely generated differential extensions L and M of K, an important problem in differential algebra is to exhibit a common differential extension N in order to define the new differential extensions L∩M and the smallest differential field (L,M ) ⊂ N containing both L and M. Such a result allows to generalize the use of complex numbers in classical algebra. Having now two finitely generated differential modules L and M over the non-commutative ring D = K [d1,...,dn] = K [d] of differential operators with coefficients in K, we may similarly look for a differential module N containing both L and M in order to define L∩M and L+M. This is exactly the situation met in linear or non-linear OD or PD control theory by selecting the inputs and the outputs among the control variables. However, in many recent books and papers, we have shown that controllability was a built-in property of a control system, not depending on the choice of inputs and outputs. The purpose of this paper is thus to revisit control theory by showing the specific importance of the two previous problems and the part plaid by N in both cases for the parametrization of the control system. An important tool will be the study of differential correspondences, a modern name for what was called Bäcklund problem during the last century, namely the elimination theory for groups of variables among systems of linear or nonlinear OD or PD equations. The main difficulty is to revisit differential homological algebra by using noncommutative localization as a way to generalize the symbolic calculus in the style of Heaviside and Mikusinski. Finally, when M is a D-module, this paper is using for the first time the fact that the system R = homK (M,K) is a D-module for the Spencer operator acting on sections, avoiding thus behaviours, trajectories and signal spaces in a purely formal way, contrary to a few recent works on this difficult subject.

Grid-Connected Control Strategy of VSG under Complex Grid Voltage Conditions

Under complex grid conditions,the grid voltage usually has an imbalance,low order harmonics,and a small of DC bias.When the grid voltage contains low order harmonics and a small amount of DC bias component,the inverter’s output current cannot meet the grid connection requirements,and there is a three-phase current imbalance in the control strategy of common VSG under unbalanced voltage.A theoretical analysis of non-ideal power grids is carried out,and a VSG control strategy under complex operating conditions is proposed.Firstly,the third-order generalized integrator(TOGI)is used to eliminate the influence of the DC component of grid voltage.An improved delay signal cancellation(DSC)method is proposed to control the balance current and power fluctuation under unbalanced voltage based on the method of common VSG positive and negative sequence separation,It also eliminates the harmonic of command current.Then,the improved quasi proportional resonant controller(QPR)cascaded PI is used to suppress the harmonic current further so that the harmonic content of grid-connected current can meet the grid-connected requirements and achieve the three-phase current balance.Finally,the proposed strategy is verified by simulation under the control objectives of the current balance,active power,and reactive power constant.

我国猪瘟流行现状及净化之路

猪瘟(Classical swine fever,CSF)在全球多个地区仍在流行,对养猪业带来巨大打击和经济损失。当前我国猪瘟防控程度较好,疫情态势平稳,偶有散发,但猪瘟的存在不利于健康养殖,影响猪肉市场及品质,因此有必要开展猪瘟净化工作。随着养猪产业不断升级,小散户逐渐退出市场,猪瘟监测技术成熟完善以及政府大力推动动物疫病净化,开展猪瘟净化时机日趋成熟,但猪瘟净化面临着非典型猪瘟、混合感染、免疫失败、动物移动等问题和挑战。本文将从我国猪瘟流行态势与防控现状,猪瘟净化的必要性与策略、面临的问题与挑战以及借鉴欧美猪瘟净化经验,采取猪瘟净化措施手段等方面进行阐述,以期为我国猪瘟净化提供理论帮助。

高压氧舱恒湿平压系统的设计

目的:设计一种高压氧舱恒湿平压系统,以消除舱内静电火花造成的危害,保证氧舱的安全运行。方法:该系统的硬件主要由加湿装置、除湿装置、平压装置、主控制器、压力传感器、温湿度传感器等组成。其中,加湿装置主体为经过特殊加工后的防爆过滤瓶;除湿装置采用工业级风机过滤单元(fan filter unit,FFU),由蒸发器、冷凝器、风轮3个部分组成;平压装置主要由电磁阀和减压管路组成;主控制器选用EX3G-C系列PLC触摸屏一体机,温湿度传感器选用NWSF-1AT型号温湿度传感器,压力传感器选用TXYS-G1K2HN3型变送器。系统的软件控制程序采用指令表语言编程,通过PID(proportional-integral-derivative)控制算法实现整体控制。结果:经过测试,该系统可使高压氧舱内相对湿度恒定在70%,使舱内极难产生静电。结论:该系统能够调节氧舱内的湿度、减少静电火花产生,保证舱内治疗的安全。

高速铁路三维控制网粗差实时判别方法研究

高速铁路三维控制网外业观测易受不利环境因素影响,难免存在测量粗差,为了尽早识别测量粗差,提高外业数据质量及后续平差结果的精度,需进行三维控制网粗差实时判别方法的研究。根据三维控制网网形及其特点,详细分析三维控制网闭合环的类型,采用三维控制网(Ⅰ类、Ⅱ类、Ⅲ类)22种闭合环进行闭合差计算;同时,基于协方差传播定律构建闭合环校核边中误差的数学模型,以2倍闭合环相对中误差为限差,判别三维控制网外业数据质量。研究表明,三维控制网网形具有较强的规律性和对称性,在完成归整后,可使用1/7000,1/13000和1/23000为对应闭合环的极限误差进行粗差判别。研究结果表明,在三维控制网外业数据观测过程中,采用该方法能够实时判别并发现测量粗差,有利于以最小代价进行现场补测,从而提高三维控制网数据可靠性和数据质量。

船舶iCER系统除雾器模拟计算与性能优化

为了得到折流板除雾器的最优运行工况,并对除雾器进行优化改进,基于智能废气再循环(iCER)系统除雾需求,选择2种转折角度(120°和135°)的除雾器进行模拟计算,分析转折角度、液滴速度和液滴粒径等3种因素对除雾效率和压降的影响,结果表明:液滴粒径越大,除雾器的除雾效果越好;液滴速度越大,除雾器的除雾效果越好;转折角度为120°的除雾器相比转折角度为135°的除雾器除雾效果更好,但压降更大。研究除雾器的优缺点,设计一种带半圆板的新型除雾器,试验结果证明其具有高效率、低压降的特点,是一种符合iCER系统试验要求的除雾器。

超高层办公建筑暖通空调系统噪声控制分析

营造良好的室内声环境对人员身心健康至关重要。本文以某超高层办公楼为研究对象,分析了超高层办公建筑声学方面的特点、典型暖通空调系统的噪声传递途径;针对办公楼层剖析了声源降噪、隔绝机房噪声、办公区内空调末端及管道的噪声控制措施,并针对机电层的不同设备区域提出了相应的隔振、隔声、降噪做法。

基于SHEPWM的三电平三相逆变器中点电位主动平衡控制策略

在大功率系统中,常采用特定次谐波消除脉宽调制(SHEPWM)以降低系统的开关损耗。针对三电平中点钳位(NPC)型三相逆变器在SHEPWM下的中点电位偏移问题,分析SHEPWM下逆变器输出相电压基波与3次谐波在不同电压相位范围内对中点电位的影响,设计两种在基波周期内对中点电位总充放电效果相反的开关角组合方案,并提出一种通过测量中点电位偏移值及中点电位滞环控制,选择不同的开关角组合方案进行调制的中点电位主动平衡控制策略。实验结果验证了所提出方法的实用性及有效性。

Moving from control to elimination of schistosomiasis in sub-Saharan Africa:time to change and adapt strategies

Schistosomiasis is a water borne parasitic disease of global importance and with ongoing control the disease endemic landscape is changing.In sub-Saharan Africa,for example,the landscape is becoming ever more heterogeneous as there are several species of Schistosoma that respond in different ways to ongoing preventive chemotherapy and the inter-sectoral interventions currently applied.The major focus of preventive chemotherapy is delivery of praziquantel by mass drug administration to those shown to be,or presumed to be,at-risk of infection and disease.In some countries,regional progress may be uneven but in certain locations there are very real prospects to transition from control into interruption of transmission,and ultimately elimination.To manage this transition requires reconsideration of some of the currently deployed diagnostic tools used in surveillance and downward realignment of existing prevalence thresholds to trigger mass treatment.A key challenge will be maintaining and if possible,expanding the current donation of praziquantel to currently overlooked groups,then judging when appropriate to move from mass drug administration to selective treatment.In so doing,this will ensure the health system is adapted,primed and shown to be cost-effective to respond to these changing disease dynamics as we move forward to 2020 targets and beyond.

Sustaining the gains made in malaria control and elimination

Significant progress has been made in the last 25 years to reduce the malaria burden,but considerable challenges remain.These gains have resulted from large investments in a range of control measures targeting malaria.Fana and co-authors find a strong relationship between education level and net usage with malaria parasitemia in pregnant women,suggesting the need for targeted control strategies.Mayala and co-workers find important links between agriculture and malaria with implications for inter-sectoral collaboration for malaria control.

From control to elimination:a spatial-temporal analysis of malaria along the China-Myanmar border

Background: Malaria cases have declined significantly along the China-Myanmar border in the past 10 years and this region is going through a process from control to elimination.The aim of this study is to investigate the epidemiology of malaria along the border,will identify challenges in the progress from control to elimination.Methods:: National reported malaria cases from China and Myanmar,along with the data of 18 Chinese border counties and 23 townships in Myanmar were obtained from a web-based diseases information reporting system in China and the national malaria control program of Myanmar,respectively.Epidemiological data was analyzed,including the number of reported cases,annual parasite index and proportion of vivax infection.Spatial mapping of the annual parasite index(API)at county or township level in 2014 and 2018 was performed by ArcGIS.The relationship of malaria endemicity on both sides of the border was evaluated by regression analysis.Results: The number of reported malaria cases and API declined in the border counties or townships.In 2014,392 malaria cases were reported from 18 Chinese border counties,including 8.4%indigenous cases and 91.6%imported cases,while the highest API(0.11)was occurred in Yingjiang County.There have been no indigenous cases reported since 2017,but 164 imported cases were reported in 2018 and 97.6%were imported from Myanmar.The average API in 2014 in 23 Myanmar townships was significantly greater than that of 18 Chinese counties(P<0.01).However,the API decreased significantly in Myanmar side from 2014 to 2018(P<0.01).The number of townships with an API between 0 and 1 increased to 15 in 2018,compared to only five in 2014,while still four townships had API>10.Plasmodium vivax was the predominant species along the border.The number of reported malaria cases and the proportion of vivax infection in the 18 Chinese counties were strongly correlated with those of the 23 Myanmar townships(P<0.05).Conclusions: Malaria elimination is approaching along the China-Myanmar border.However,in order to achieve the malaria elimination in this region and prevent the re-establishment of malaria in China after elimination,continued political,financial and scientific commitment is required.

Is onchocerciasis elimination in Africa feasible by 2025:a perspective based on lessons learnt from the African control programmes

Background:Onchocerciasis is found predominantly in Africa where large scale vector control started in 1974.Registration and donation of ivermectin by Merck&Co in 1987 enabled mass treatment with ivermectin in all endemic countries in Africa and the Americas.Although elimination of onchocerciasis with ivermectin was considered feasible only in the Americas,recently it has been shown possible in Africa too,necessitating fundamental changes in technical and operational approaches and procedures.Main body:The American programme(OEPA)operating in onchocerciasis epidemiological settings similar to the mild end of the complex epidemiology of onchocerciasis in Africa,has succeeded in eliminating onchocerciasis from 4 of its 6 endemic countries.This was achieved through biannual mass treatment with ivermectin of 85%of the eligible population,and monitoring and evaluation using serological tests in children and entomological tests.The first African programme(OCP)had a head start of nearly two decades.It employed vector control and accumulated lots of knowledge on the dynamics of onchocerciasis elimination over a wide range of epidemiological settings in the vast expanse of its core area.OCP made extensive use of modelling and operationalised elimination indicators for entomological evaluation and epidemiological evaluation using skin snip procedures.The successor African programme(APOC)employed mainly ivermectin treatment.Initially its objective was to control onchocerciasis as a public health problem but that objective was later expanded to include the elimination of onchocerciasis where feasible.Building on the experience with onchocerciasis elimination of the OCP,APOC has leveraged OCP’s vast modelling experience and has developed operational procedures and indicators for evaluating progress towards elimination and stopping ivermectin mass treatment of onchocerciasis in the complex African setting.Conclusions:Following the closure of APOC in 2015,implementation of onchocerciasis elimination in Africa appears to overlook all the experience that has been accumulated by the African programmes.It is employing predominantly American processes that were developed in a dissimilar setting from the complex African onchocerciasis setting.This is impeding progress towards decisions to stop intervention in many areas that have reached the elimination point.This article summarizes lessons learned in Africa and their importance for achieving elimination in Africa by 2025.

C92K型数控全液压模锻锤常见故障分析与维护

数控全液压模锻锤是目前世界上最先进的模锻设备,既可以实现打击能量及工序的数字化控制,也可以实现自动化连线。结合对数控全液压模锻锤工作原理及结构特点,对其常见故障的排除方法及日常维护进行归纳总结。

海虾加工过程中微生物污染的控制与消除技术研究

本文阐述海虾加工行业的重要意义,分析微生物污染的主要来源与影响,探讨海虾加工过程中微生物污染的控制技术以及消除技术,旨在提升海虾加工产品的质量,保障消费者健康。

From river blindness control to elimination:bridge over troubled water

Background:An estimated 25 million people are currently infected with onchocerciasis(a parasitic infection caused by the filarial nematode Onchocerca volvulus and transmitted by Simulium vectors),and 99%of these are in sub-Saharan Africa.The African Programme for Onchocerciasis Control closed in December 2015 and the World Health Organization has established a new structure,the Expanded Special Project for the Elimination of Neglected Tropical Diseases for the coordination of technical support for activities focused on five neglected tropical diseases in Africa,including onchocerciasis elimination.Aims:In this paper we argue that despite the delineation of a reasonably well-defined elimination strategy,its implementation will present particular difficulties in practice.We aim to highlight these in an attempt to ensure that they are well understood and that effective plans can be laid to solve them by the countries concerned and their international partners.Conclusions:A specific concern is the burden of disease caused by onchocerciasis-associated epilepsy in hyperendemic zones situated in countries experiencing difficulties in strengthening their onchocerciasis control programmes.These difficulties should be identified and programmes supported during the transition from morbidity control to interruption of transmission and elimination.

静力学辨识力矩补偿控制抑制机械臂振动研究

机械臂在完成定位抓取时,由于本身存在柔性引起振动影响机械臂的工作效率。因此,大多专家学者通过设计控制器进行开环前馈控制,但由于忽略机械臂关节端摩擦和电机端摩擦等非线性因素,控制器控制精度不足,抑制关节振动效果欠佳。对此提出通过静力学辨识得到准确的摩擦力矩补偿量,设计精确的关节力矩补偿控制律。最后,通过MATLAB仿真验证方法的有效性。