Modeling and Sliding Mode Control with Boundary Layer for Unmanned Coaxial Rotor Ducted Fan Helicopter

The structure and modeling of a novel unmanned coaxial rotor ducted fan helicopter(RDFH)are introduced,and then,based on the helicopter air dynamics and kinematics principles,a nonlinear model of the coaxial rotor ducted fan helicopter is developed and implemented on the basis of the wind tunnel experiment.After that,the helicopter′s stability and coupling characteristics of manipulation are analyzed through time-domain.Finally,a sliding mode controller(SMC)with boundary layers is developed on a hardware in the loop platform using digital signal processor(DSP)as the flight control computer.The results show that the RDFH′s tracking ability performs well under the use of proposed controller.

Automation in detection of recirculation in a booster fan ventilation network

Recirculation is prohibited in many coal mining countries because of the fear that the re-use of return air would allow the build-up of air contaminants at the workings. The incorrect design and location of a booster fan in any ventilation network can create unsafe condition due to recirculation. The current approach to investigating recirculation using simulation software requires manual effort which becomes tedious in a complex and a large network. An algorithm-based C++ program was designed to detect the recirculation in a booster fan ventilation networks. This program needed an input file prepared from output file generated by any ventilation simulator. This program created an output file for recirculation. This program demonstrated the strong capability to detect the recirculation in a sample network and a coal mine ventilation network. The outcomes of this program were documented in this paper.

Design of a Three-Dimensional Centrifugal Fan with Controlled Blade Loading Approach

The high flow-rate centrifugal fan needs a three-dimensional impeller to achieve a high efficiency. In this paper, the design procedure of a high-efficiency three-dimensional centrifugal fan is presented. First, the main dimensions of the fan were calculated by using the conventional one-dimensional method. Then, the blade loading or the angular momentum distribution along the meridional streamline on the blade surfaces is prescribed. After that, the three-dimensional blade is determined by using the streamline curvature method. With the aid of numerical simulations, the performance of the three-dimensional fan was improved and some of the key influence factors were investigated. The analyses indicate that, as to the high flow-rate centrifugal fan, the Stanitz modified formula is recommended to calculate the separation radius, rb. A proper increase in the separation radius is beneficial for the fan’s performance. It is also indicated that a decrease in the angular momentum on the hub leads to an increase in total pressure efficiency, under the condition of a given constant mean angular momentum at the outlet of the blade. In addition, the installation of a fairing on the hub plate can improve the fan’s efficiency evidently when the streamline curvature method is adopted to design the three-dimensional impeller.

Evolution and controlling factors of the gravity flow deposits in the Miocene sequence stratigraphic framework,the Lower Congo-Congo Fan Basin,West Africa

To understand the evolution of the Miocene gravity flow deposits in the Lower Congo-Congo Fan Basin,this paper documents the Miocene sequence stratigraphic framework,the depositional characteristics and the controlling factors of the gravity flow system.Based on the establishment of high-resolution sequence stratigraphic framework,lithofacies characteristics and sedimentary units of the gravity flow deposits in the region are identified by using seismic,well logging and core data comprehensively,and the sedimentary evolution process is revealed and the controlling factors are discussed.The Miocene can be divided into four 3 rd-order sequences(SQ1-SQ4).The gravity flow deposits mainly include siliciclastic rock and pelite.The main sedimentary units include slumping deposits,mass transport deposits(MTD),channel fills,levee-overbank deposits,and frontal lobes.In the Early Miocene(SQ1),mainly gull-wing,weakly restricted to unrestricted depositional channel-overbank complexes and lobes were formed.In the early Middle Miocene(SQ2),W-shaped and weakly restricted erosional-depositional channels(multi-phase superposition)were subsequently developed.In the late Middle Miocene(SQ3),primarily U-shaped and restricted erosional channels were developed.In the Late Miocene(SQ4),largely V-shaped and deeply erosional isolated channels were formed in the study area.Climate cooling and continuous fall of the sea level made the study area change from toe of slope-submarine plain to lower continental slope,middle continental slope and finally to upper continental slope,which in turn affected the strength of the gravity flow.The three times of tectonic uplifting and climate cooling in the West African coast provided abundant sediment supply for the development of gravity flow deposits.Multistage activities of salt structures played important roles in redirecting,restricting,blocking and destroying the gravity flow deposits.Clarifying the characteristics,evolution and controlling factors of the Miocene gravity flow deposits in the Lower Congo-Congo Fan Basin can provide reference for deep-water petroleum exploration in this basin.

Use of booster fans in underground coal mining to advantage

A booster fan is an underground main fan which is installed in series with a main surface fan and used to boost the air pressure of the ventilation to overcome mine resistance.Currently booster fans are used in several major coal mining countries including the United Kingdom,Australia,Poland and China.In the United States booster fans are prohibited in coal mines although they are used in several metal and non-metal mines.A study has been undertaken to examine alternatives for ventilating an underground room and pillar coal mine system.A feasibility study of a hypothetical situation has shown that current ventilation facilities are incapable of fulfilling mine air requirements in the future due to increased seam methane levels.A current ventilation network model has been prepared and projected to a mine five years plan."Ventsim visual" software simulations of different possible ventilation options have been conducted in which varying methane levels are found at working faces.The software can also undertake financial simulations and project present value total costs for the options under study.Several scenarios for improving the ventilation situation such as improving main surface fans,adding intake shafts,adding exhaust shafts and utilizing booster fans have been examined.After taking into account the total capital and operating costs for the five years mine plan the booster fan scenarios are recommended as being the best alternatives for further serious consideration by the mine.The optimum option is a properly sized and installed booster fan system that can be used to create safe work conditions,maintain adequate air quantity with lowest cost,generate a reduction in energy consumption and decrease mine system air leakage.

Influence of Wall Effect on Comprehensive Controllability for Ducted Fan Aircraft

A novel coaxial ducted fan structure aircraft is proposed to enable the aircraft near vertical walls at high altitudes.The state space equation of the system can be obtained by correlation deduction and identification of the whole prototype model.Based on the duct test bench experiment and computational fluid dynamics(CFD)simulation analysis,the expressions between the different distances dWE from the rotor center of the prototype to the wall and the thrust,reaction torque,and tilting moment of the system under hovering conditions are obtained.The influence of the wall effect of the prototype is incorporated into the system model to analyze the relationship between distance dWE and the comprehensive controllability of the system.The results show that the system comprehensive controllability vector of other channels changes little with the decrease of the distance dWE,and only the controllability vector of the rolling channel increases significantly.At the same time,the tilting moment also increases significantly,which strengthens the tendency of the prototype to tilt towards the wall.

Solid Rocket Booster Thrust Asynchrony Identification Method for Solid Rocket Bundled Rockets With ESO

The role of the rocket attitude control system is to execute the required maneuvers for guidance and ensure the stability of the rocket's flight attitude. Attitude control technology has always been one of the key technologies for ensuring the success of rocket flights and has been a core topic in carrier rocket technology research. The Gravity-1 solid carrier rocket is the first solid rocket bundled rocket developed by China, adopting a configuration with four boosters and a core stage bundled together. During the actual flight process, the four booster engines are ignited first, and then, in the event of insufficient control force from the boosters, the core stage engine is ignited to participate in control. To address thrust asynchrony during the descent of the four boosters, an Extended State Observer(ESO) is employed in the control scheme for this flight segment. This involves real-time estimation and compensation of attitude parameters during flight, identification of thrust asynchrony among the boosters, and simultaneous determination of whether the core stage engine is ignited to participate in control.Through six degrees of freedom simulation analysis and Y1 flight test validation, this method has been proven to be correct and feasible.

Temperature-Based Fan Speed Optimization Strategy

As energy efficiency and indoor comfort increasingly become key standards in modern residential and office environments,research on intelligent fan speed control systems has become particularly important.This study aims to develop a temperature-feedback-based fan speed optimization strategy to achieve higher energy efficiency and user comfort.Firstly,by analyzing existing fan speed control technologies,their main limitations are identified,such as the inability to achieve smooth speed transitions.To address this issue,a BP-PID speed control algorithm is designed,which dynamically adjusts fan speed based on indoor temperature changes.Experimental validation demonstrates that the designed system can achieve smooth speed transitions compared to traditional fan systems while maintaining stable indoor temperatures.Furthermore,the real-time responsiveness of the system is crucial for enhancing user comfort.Our research not only demonstrates the feasibility of temperature-based fan speed optimization strategies in both theory and practice but also provides valuable insights for energy management in future smart home environments.Ultimately,this research outcome will facilitate the development of smart home systems and have a positive impact on environmental sustainability.

The early-middle Miocene submarine fan system in the Pearl River Mouth Basin, South China Sea

Based on a large amount of seismic, drilling and core data, the characteristics of the early- middle Miocene submarine fans in the Baiyun Sag, northern South China Sea are investigated. By analyzing the sedimentary processes of submarine fans in SQ21 （SQ21 refers to the 3rd-order sequence with its bottom boundary 21 Ma）, a sedimentary model of the sand-rich fans is established and the main factors controlling fan deposition are detailed. The results indicate that from early to middle Miocene the Pearl River Mouth Basin developed seven 3rd-order sequences in all, with each lowstand systems tract （LST） of the sequence corresponding to submarine fans. However, only the fans in SQ13.8 and SQ21 are sand-rich fans, the others being mud-rich fans. The cores reveal that the submarine fans in the Pearl River Mouth Basin developed five lithofacies： （1） mud clast-bearing sandstone, interpreted as channel deposits; （2） typical turbidite sandstones, also interpreted as channel deposits; （3） thin-bedded sandstone and mudstone, interpreted as channel-levee complex deposits; （4） massive sandstones, interpreted as lobe deposits; （5） massive mudstone, interpreted as hemipelagic mud. The sand-rich submarine fans in the Pearl River Mouth Basin mainly developed in LST, and in LST reverse faults were active, which led to the formation of accommodation on the shelf. Different from the theory of classic sequence stratigraphy, the accommodation on the shelf captures terrigenous debris transported by the Pearl River, and the uplift at the edge of shelf serves as a ＂Linear Source＂ for the deep water area instead of the Pearl River. Therefore, the fans mainly derived from the eroded debris from the uplift. Factors controlling fan deposition include the basin＇s tectonic framework, the evolution of the slope break, relative sea-level changes as well as the evolution of the fault system, and the fans are formed under the combination of the above factors.

Design of the Control System of Adaptive Balancing Device Based on PLC

Due to the well condition and the un-expected imbalance movement of the pumping unit in use, the energy consumes a lot. The existing balancing equipment cannot adjust and monitor the pumping units in real time. Therefore this paper introduces the new adaptive balancing equipment—fan-shaped adaptive balancing intelligent device, projects a design of such control system based on PLC, and determines the principle of the control system, the execution software and the design flow. Site commissioning effect on Daqing Oilfield shows this fan-shaped adaptive balancing intelligent device can effectively adjust and monitor the pumping unit in real time, the balance even adjusts from 0.787 to 0.901, and integrated energy saving rate is 14.2%. It is approved that this control device is professionally designed, with strong compatibility, and high reliability.

A global satellite survey of density plumes at river mouths and at other environments: Plume configurations, external controls, and implications for deep-water sedimentation

The U. S. National Aeronautics and Space Administration(NASA) has archived thousands of satellite images of density plumes in its online publishing outlet called 'Earth Observatory' since 1999. Although these images are in the public domain, there has not been any systematic compilation of configurations of density plumes associated with various sedimentary environments and processes. This article, based on 45 case studies covering 21 major rivers(e.g., Amazon, Betsiboka, Congo [Zaire], Copper, Hugli [Ganges], Mackenzie, Mississippi, Niger, Nile, Rhone, Rio de la Plata, Yellow, Yangtze, Zambezi, etc.) and six different depositional environments(i.e., marine, lacustrine, estuarine, lagoon, bay, and reef), is the first attempt in illustrating natural variability of configurations of density plumes in modern environments. There are, at least, 24 configurations of density plumes. An important finding of this study is that density plumes are controlled by a plethora of 18 oceanographic, meteorological, and other external factors. Examples are: 1) Yellow River in China by tidal shear front and by a change in river course; 2) Yangtze River in China by shelf currents and vertical mixing by tides in winter months; 3) Rio de la Plata Estuary in Argentina and Uruguay by Ocean currents; 4) San Francisco Bay in California by tidal currents; 5) Gulf of Manner in the Indian Ocean by monsoonal currents; 6) Egypt in Red Sea by Eolian dust; 7) U.S. Atlantic margin by cyclones; 8) Sri Lanka by tsunamis; 9) Copper River in Alaska by high-gradient braid delta; 10) Lake Erie by seiche; 11) continental margin off Namibia by upwelling; 12) Bering Sea by phytoplankton; 13) the Great Bahama Bank in the Atlantic Ocean by fish activity; 14) Indonesia by volcanic activity; 15) Greenland by glacial melt; 16) South Pacific Ocean by coral reef; 17) Carolina continental Rise by pockmarks; and 18) Otsuchi Bay in Japan by internal bore. The prevailing trend in promoting a single type of river-flood triggered hyperpycnal flow is flawed because there are 16 types of hyperpycnal flows. River-flood derived hyperpycnal flows are muddy in texture and they occur close to the shoreline in inner shelf environments. Hyperpycnal flows are not viable transport mechanisms of sand and gravel across the shelf into the deep sea. The available field observations suggest that they do not form meter-thick sand layers in deep water settings. For the above reasons, river-flood triggered hyperpycnites are considered unsuitable for serving as petroleum reservoirs in deep-water environments until proven otherwise.

STUDY ON THE AUTOMATIC REGULATION SYSTEM OF WIND RATE FUZZY CONTROL

This paper presents the solution of regulating the wind rate automatically by means of fuzzy control technology and implementing it with PLC (programmable logical controller) under the circumstance of many influence factors, which exists in the axial flow fans wind rate regulation system during the process of mine ventilation, and has difficulty in modifying the mathematic model to obtain the satisfied result by normal control ways. According to this analysis, the intelligent and analytic treatment of fuzzy controller has been made and fuzzy control scheme involving self regulation divisor and intelligent integral has been deeply proposed. Test result shows that this system based on the scheme above is obviously prior to others in its responsibility such as high speed, overshoot, control precision and robustness. The system furnishes the great reliability of mine working safety and fans running efficiency.

EVALUATION OF SMART BOOSTER FANS AND DAMPERS FOR ADVANCED HVAC SYSTEMS

There is potential to significantly reduce CO_(2) emissions by increasing the efficiency and reducing the duty cycle of HVAC systems by using smart booster fans and dampers.Smart booster fans fit in the vents within a home,operating quietly on low power(2W)to augment HVAC systems and improve their performance.In this study,a prototype duct system is used to measure and evaluate the ability for smart booster fans and dampers to control airflow to different vents for the purpose of increasing the efficiency of HVAC systems.Four case studies were evaluated:an HVAC system(1)without any fans or dampers,(2)with a fan installed in one vent,but without any dampers,(3)with dampers installed at the vents,but without any fans,and(4)with both fan and dampers installed.The results from both the experi-mental and numerical evaluation show that the smart booster fan and dampers can significantly improve the airflow at a vent that is underperforming.For example,the airflow at the last vent in a ducting branch was increased from 17 to 37 CFM when a smart booster fan was installed at this vent.Results from the numerical analysis show that for the case of an underperforming vent during the winter season the HVAC running time may be reduced from 24 hr/day to 5.6 hr/day.Furthermore,results from the numerical analysis show the HVAC running time is further reduced to 4.5 hr/day for cases 3 and 4.

Modeling and Simulation of Evaporative Cooling System in Controlled Environment Greenhouse

Greenhouses are used for the main purpose of improving the environmental conditions in which plants are grown. There are many parameters can affect the growing of plants inside greenhouse, such as air temperature and relative humidity. The adjustment of these parameters is achieved by selecting appropriate control actions. This work proposes a controlling technique for greenhouse indoor temperature and relative humidity. The proposed greenhouse cooling system temperature controller is designed to adjust the air volume flow rate in pad-fan cooling system to fix the greenhouse indoor temperature at 20?C and 70% relative humidity. The designed control technique is realized to ensure the required and continuous operation of the greenhouse. Moreover, this work present, a complete mathematical modeling and simulation of cooling system is introduced. In addition, a computer model based on MATLAB SIMULINK software has been used to predict the temperature and relative humidity profiles inside the greenhouse. The results are realized the requirements of the greenhouse cooling system environment.

汽车冷却风扇噪声主动控制仿真及声品质评价

以汽车冷却风扇噪声为研究对象,基于采集的噪声生成具有不同音调特性的模拟噪声,利用改进的音调度模型计算音调度,使用等级评分法对生成的模拟噪声进行主观评价实验。根据音调特性十分明显的旋转噪声频率与风扇转速密切相关的特点,提出以风扇转速信号来构造次级声源参考信号进行主动噪声控制。最后建立并联型灰色神经网络模型并检验降噪效果。结果表明,冷却风扇噪声的音调特性是影响感知烦恼的重要因素之一,通过有源噪声控制能有效降低窄带噪声峰值从而降低音调度。引入并联型灰色神经网络进行预测的平均相对误差为2.86%,降噪后烦恼度有较好的改善。

含减载控制和虚拟惯量控制的直驱风电场等值建模方法

为建立准确的具有主动支撑能力的直驱风电场等值模型,提出一种含减载控制和虚拟惯量控制的直驱风电场等值建模方法。首先,建立包含减载控制和虚拟惯量控制的直驱风机并网系统模型;其次,依据适应性分析选取转速、减载系数、惯性系数和阻尼系数作为分群指标;然后,基于分群指标利用改进K-means算法对直驱风电场中的机组进行聚类分群,得到直驱风电场的等值模型;最后,利用实际算例在不同场景下进行仿真和计算,对等值建模方法的准确性进行验证。

GE Fanuc公司GMR系统在大型轴流式压缩机组中的应用

本文介绍GE Fanuc公司GMR系统在大型轴流式压缩机组中的应用。概述了工艺需求，着重描述了该压缩机GMR系统的三重化结构和功能、汽轮机组电子调速控制和防喘振控制的基本原理。

锦屏复杂地下洞室施工通风智能调控研究

锦屏大设施具有多洞室、多工作面,通风网络复杂等特点,为确保洞室空气质量并解决施工期通风高能耗问题,通过优化隧道需风量计算方法,确定风压阻力损失,进行施工通风计算。根据风机布设位置,划分供排风区域,明确了风机控制区域;基于各区域风量、风压,得出了风机运行功率计算式并细分风机档位,形成了地下洞室施工期风机变频调节策略;通过布设空气质量监测设备,建立了软件平台,可视化远程控制地下洞室空气质量,自动监测、处理数据指导变频器控制风机变频,并利用污染物浓度监测数据验证了变频通风有效性。研究结果表明:1)风机运行频率可随洞室内污染物浓度及时变化;2)通风智能调控可有效降低污染物浓度;3)通风智能调控可降低施工通风能耗,实现施工期智能化通风。

有源缓冲型逆变器功率解耦技术研究

为实现单级单相升压逆变并能有效抑制直流侧二次纹波电流,提出一种带有源缓冲的电流型逆变器电路拓扑,研究该逆变器的6种电路模态并提出其两模态调制策略和三模态调制策略,设计2种调制策略下的模型预测控制策略,提供主电路参数设计准则。从储能电感电流的最大脉动量与二次纹波含量两方面对2种调制策略进行对比分析,得出了三模态调制策略具有更好纹波抑制效果的结论。对2种调制策略下的逆变器进行仿真分析,仿真结果表明,三模态调制下电路的输出电压总谐波失真率、电感电流相对脉动量与二倍频含量均低于两模态调制下的数据。设计并搭建500VA 48VDC/220V50HzAC有源缓冲型单级单相升压逆变器实验装置,给出了三模态调制下基于模型预测控制的逆变器实验波形,进一步证实了所提研究方案在实现单级升压逆变的同时具有二次纹波抑制能力。

机力通风冷却塔风机自寻优群控方法研究

机力通风冷却塔以占地面积小的显著优点,在中小型基建工程中得到广泛应用。为提升中小型基建工程外冷系统的节能性和可靠性、改进传统多风机控制方法,创新性地提出了一种基于累计运行时间的机力通风冷却塔风机自寻优群控方法。将多风机整体化控制改进为顺序化联动控制,可有效降低风机启动门槛出力、消除整体化控制固有缺陷,满足非线性、时变性、大滞后系统控制的节能、可靠需求。经工程验证:该方法是一种契合纯变频电机配置冷却塔系统的多风机控制方法。该方法风机出力柔和、控制线性度好、系统易镇定、稳态偏差小;能够通过累计运行时间参数比对,实现风机自动交互运行,运行可靠性高。该方法的提出与实际应用可对配置机力通风冷却塔的中小型基建工程的安全节能运行提供借鉴。