Influence of propagation direction on operation performance of rotating detonation combustor with turbine guide vane

Due to the pressure gain combustion characteristics,the rotating detonation combustor(RDC)can enhance thermodynamic cycle efficiency.Therefore,the performance of gas-turbine engine can be further improved with this combustion technology.In the present study,the RDC operation performance with a turbine guide vane(TGV)is experimentally investigated.Hydrogen and air are used as propellants while hydrogen and air mass flow rate are about 16.1 g/s and 500 g/s and the equivalence ratio is about 1.0.A pre-detonator is used to ignite the mixture.High-frequency dynamic pressure transducers and silicon pressure sensors are employed to measure pressure oscillations and static pressure in the combustion chamber.The experimental results show that the steady propagation of rotating detonation wave(RDW)is observed in the combustion chamber and the mean propagation velocity is above 1650 m/s,reaching over 84%of theoretical Chapman-Jouguet detonation velocity.Clockwise and counterclockwise propagation directions of RDW are obtained.For clockwise propagation direction,the static pressure is about 15%higher in the combustor compared with counterclockwise propagation direction,but the RDW dominant frequency is lower.When the oblique shock wave propagates across the TGV,the pressure oscillations reduces significantly.In addition,as the detonation products flow through the TGV,the static pressure drops up to 32%and 43%for clockwise and counterclockwise propagation process respectively.

Empirical analysis of mass flow and operation performance of a full-scale biogas plant for human feces treatment

With the rapid development of urbanization in China,the existing municipal network cannot cover all areas and solve all human waste treatment problems.Biogas plants,as an important nationally developmental strategy for cleaner energy production and environmental protection,have been widely used in many industrial and agricultural fields.This research analyzed the mass flow and operation performance in a biogas plant treating human feces at a practical rather than laboratory scale.The biogas plant operated on mesophilic semi-continuous mode at the organic loading rates(OLRs)of 0.56 kg volatile solid(VS)/(m³·d)and average total solid(TS)contents of 3.50%.Results showed that the average biogas production and methane yield were(145±10)m³/d and(471±17)m³CH4/(t VS),respectively.Annual total feeding amount was 2555.0 t.Among these,there were 58.04 t biogas and 2496.97 t digestate,including 43.07 t solid residues and 2453.90 t liquid digestate.For the full-scale biogas plant,anaerobic bacteria could acclimatize to high total ammonia nitrogen(TAN)concentration(3659 mg/L)and tolerate high free ammonia nitrogen(FAN)concentration of 561 mg/L.It also had strong autoregulation for adapting the large range(2.02-15.18 g/L)and high concentration(15.18 g/L)of influent volatile fatty acid(VFA).In order to achieve its sustainable development and high efficient operation,it is very important to improve the feeding concentration,using digestate to dilute raw material and adding some high C/N raw material in human feces.In conclusion,the biogas plant was an excellent alternative technology for treating human feces.

SEMG-based fighter pilot muscle fatigue analysis and operation performance research

Fatigue has a tremendously adverse impact on pilot performance.This study aims to explore the Biceps Brachii(BB),Rectus Femoris(RF),Flexor Carpi Radialis(FCR),and Tibialis Anterior(TA)activities of fighter pilots in the early and late combat stages,and the target hitting time.A total of 13 volunteers were recruited to conduct simulated combats inside a real fighter cockpit.The surface Electromyography(sEMG)was collected from all volunteers in the initial and final 20s of flight,and the target hitting time during three simulated combats was recorded.The root mean square(RMS)values of right BB and TA were significantly higher than the left side values(p<0.001),while insignificant differences were found in the RMS values between the bilateral RF and FCR.Compared to the early flight period,the median frequency(MF)values of BB and TA were significantly lower during the late flight period,and the RMS values were significantly higher(p<0.047).Contrastively,the RMS values of FCR and RF differed insignificantly during the late flight period.Regarding the target hitting time,a significant difference was noted between task 1 and rask3.Subjects exhibit varying levels of muscle fatigue for different muscle groups before and after the flight.The muscle fatigue levels are asymmetrical on the left and right sides.Muscle fatigue might reduce the pilots'operational ability.This study provides a reference for fighter pilot fatigue protection and treatment.

Heuristics for Improving Operational Performance of Permutation Circulati on-type Vehicle Routing System

This paper discusses an optimization of operating a p ermutation circulation-type vehicle routing system (PCVRS, for short), in w hich several stages are located along by a single loop, and a fleet of vehicles travels on the loop unidirectionally and repeatedly. Traveling on the loop, each vehicle receives an object from the loading stage and then carries it to a cert ain processing stage, or receives an object from a certain processing stage and then carries it to the unloading stage per a turnaround. No passing is allowed f or the vehicles on the loop (from which the system is called permutation, and th is restriction may cause interferences between vehicles). Material handling systems such as PCVRS are actually encountered in flexible man ufacturing systems and in automated storage/retrieval systems. In this paper, we propose a heuristic algorithm for operating the PCVRS, which i ncorporates a new scheduling method for the vehicles with the SPT (shortest proc essing time) numbering of jobs and a round-robin manner of allocating jobs to t he stages, aiming to reduce interferences between the vehicles. We also give num erical results with respect to system performances attained by the heuristic. Description of the system The PCVRS consists of a set of n v vehicles V={V 1,V 2,...,V n v}, a set of n s, processing stages S p={S 1,S 2,...,S n s}, a loading stage S 0 and an unloading stage S n s +1. We denote by S=S p∪{S 0,S n s+l} the set of all the stages. The vehicles travel on a single loop unidirectionany and repeated ly. The system layout is depicted in Fig.1. There is a set of n jobs J={J 1,J 2,...,J n} to be processed b y the vehicles. Each job consists of two tasks: That is, each vehicle receives a n object from S 0 and then carries it to S l with a certain l∈{1,2, ...,n s} (a throw-in job), or receives an object from S l with a certain l∈{1,2,...,n s} and then carries it to S n s+1 (a throw-out job ) per a turnaround. The loop consists of buffer zones BZ(l) and travel zones TZ(l) (see Fig. 1). Each buffer zone BZ(l) is placed in front of stage S l, l=0,1,..., n s, n s+1, in order to avoid a collision between vehicles (i.e., the syste m adopts the so-called zone control strategy). A heuristic algorithm We develop a heuristic algorithm to obtain a good performance for the PCVRS. An operation π={A/B/C} for the PCVRS consists of three decision factors: (A) Numbering jobs Jobs are loaded into S 0 according to an assending order of job numbers. In this paper, we use the following rules to number jobs: SPT: Order jobs in the shortest processing time rule, i.e., P 1≤P 2≤...≤P n for the set of jobs J={J 1,J 2,...,J n}, rather than the FCFS numbering (i.e., number jobs in first-come-first-served order). The SPT rule intends to reduce interferences between two adjacent vehicles at stages. (B) Allocating jobs to stages For the purpose of balancing loads of processing stages, we adopt the following to allocate jobs to the stages: ORDER: Allocate n jobs to n s, processing stages by an in-order manner , i.e., let l(i) be the index of processing stage allocated job J i by ORDER, it holds that l(i)=n s+1-(i-[(i-1)/n s]n s).(1) The ORDER rule intends to process jobs parallel at stages as many as possible. (C) Scheduling vehicles The following method for scheduling vehicles under ORDER rule is already known: Fig.1 The vehicle ro uting system, PCVRS Fig.2 Mean turnaroun d times by heuristics Unchange: Assign n jobs to n v vehicles such that let k(i) be the i ndex of vehicle processing job J i, then k(i)= i-[(i-1)/n v]n v.(2) In csse of n v≥n s, mod (n v,n s)=0 or n v<n s, mod (n s,n v)=0 (mod(x,y) is the remainder of x/y), the number of interferences between vehicles is minimized at stage S 1 under Unchange sche dules, while in the other cases it is not [Lu et al. (2001a)]. Therefore, in t his paper, we develop a new scheduling method of the vehicles, denoted by Ex change, to modify Unchange schedules. Note

Flower Farms Environmental Performance Evaluation in Ethiopia

Cultivation of cut flowers is a new agricultural sector in Ethiopia,which currently generates a high amount of income for the country's develop­ments.Despite its significant contribution to economic developments;many issues were raised from communities and environmentalists con­cerning its environmental performance.Based on this issue the study as­sesses cradle to gate of cut flower production in the Wolmera district.The main objective of the study was environmental performance evaluation of flower farms in Wolmera district,Oromia regional state,Ethiopia related to operational activities throughout entire life cycles of cut flower pro­duction.In this study,primary and secondary data were collected using ISO 14031 standard structured with LCA tool methodology.Data were collected by inventory using an on-site data collection system from its sources.Based on data collected GHG(CO2,N2O,CH4&NH3)emissions to the atmosphere were evaluated by using an inter-governmental panel on climatic changes(IPCC 2006)for inventory data and eutrophication&acidification estimated from data tested at laboratory levels.Similarly,the study also assesses banned chemicals used in the farms through invento­ry data assessment,and about 156 chemicals applied in the farms were collected to screen out those banned chemicals used and the two most extremely hazardous chemicals(Impulse&Meltatix)banned by WHO identified in the study.As it understood from a general assessment of all flower farms;all of them haven't EIA document established before con­struction in the district and production started with having less attention for EHPEA code of conducts in the flower farms which faces the envi­ronments for high impacts by emission emitted from flower farms in the district as a whole.

Performance of Gas-Steam Combined Cycle Cogeneration Units Influenced by Heating Network Terminal Steam Parameters

The determination of source-side extracted heating parameters is of great significance to the economic operation of cogeneration systems.This paper investigated the coupling performance of a cogeneration heating and power system multidimensionally based on the operating characteristics of the cogeneration units,the hydraulic and thermodynamic characteristics of the heating network,and the energy loads.Taking a steam network supported by a gas-steam combined cycle cogeneration system as the research case,the interaction effect among the source-side prime movers,the heating networks,and the terminal demand thermal parameters were investigated based on the designed values,the plant testing data,and the validated simulation.The operating maps of the gas-steam combined cycle cogeneration units were obtained using THERMOFLEX,and the minimum source-side steam parameters of the steam network were solved using an inverse solution procedure based on the hydro-thermodynamic coupling model.The cogeneration operating maps indicate that the available operating domain considerably narrows with the rise of the extraction steam pressure and flow rate.The heating network inverse solution demonstrates that the source-side steam pressure and temperature can be optimized from the originally designed 1.11 MPa and 238.8°C to 1.074 MPa and 191.15°C,respectively.Under the operating strategy with the minimum source-side heating parameters,the power peak regulation depth remarkably increases to 18.30%whereas the comprehensive thermal efficiency decreases.The operation under the minimum source-side heating steam parameters can be superior to the originally designed one in the economy at a higher price of the heating steam.At a fuel price of$0.38/kg and the power to fuel price of 0.18 kg/(kW·h),the critical price ratio of heating steam to fuel is 119.1 kg/t.The influence of the power-fuel price ratio on the economic deviation appears relatively weak.

A systematic approach for estimating water losses in irrigation canals

In order to determine water losses in irrigation canals,a systematic approach was developed,consisting of two main components:a seepage simulation model and a hydraulic simulation model.The SEEP/W module of the Geo-Studio software was used to simulate the seepage rate,and the Hydrologic Engineering Center-River Analysis System(HEC-RAS)hydrodynamic model was used for hydraulic simulation.Different operation scenarios were designed to investigate all possible situations in daily operation of water distribution and delivery systems.The seepage simulation results show that the seepage losses were higher at the bottom and corners of the canal,because the hydraulic gradient was affected by the hydraulic load.The hydraulic simulation results show that due to physical and management infrastructure(using non-automated and operator-based regulation structures),operational losses accounted for a significant volume of losses compared to seepage losses.In most operation scenarios,the maximum seepage loss was 10%,and the remaining 90%was related to operational losses.It is concluded that any factor(decrease or increase of inflow to the canal)that causes an increase or decrease of operational losses is ultimately a determining factor in reducing or increasing total losses.Therefore,management approaches should be adopted to improve performance of the system and reduce losses,especially operational losses,by improving the operation methods of water level regulation and off-take structures.

Field Investigation and Comparison Analysis of Low-Grade Heat Pump Technologies in Building Space Heating Projects

The building sector contributes a large ratio of final energy consumption,and improving building energy efficiency is expected to play a significant role in mitigating its carbon dioxide emission.Herein,we collected the on-site measurement data to investigate the techno-economic performances of different heat pump types that exist in building space heating projects in Qingdao,China.An in-depth analysis revealed the temperature variations of measured low-grade heat sources over the whole heating supply period,and urban sewage water shows high stable heat energy quality compared with seawater and geothermal heat resources.Operational behaviors including cycling inlet and outlet temperature of the selected heat pumps were illustrated,and analysis evaluated detailed effects of operational parameters on energy efficiency performances.Then the relationship between COPs distributions of heat pumps and operational conditions was examined further,and the positive effect of the rising temperature of heat sources on energy efficiency improvement of heat pump is highlighted when the heating supply temperature is higher.Furthermore,we analyzed the economic and carbon emission performance of the heat pump system,and results show that electricity price plays a vital role in the lifespan energy cost saving potential,and the heat pump could serve as a promising approach in reducing CO_(2) related to the building space heating.Finally,we recommended suggestions for improving the overall energy efficiency and cost competitiveness of decentralized heat pump systems for building space heating.

Analysis and Evaluation of Thermal-cooling Loads of Office Buildings Using Carrier Software in Iran

The importance and necessity of energy saving in the world have been dis­cussed for many years,but achieving a logical and transparent solution is still one of the main challenges and problems of the world’s economy.The rapid growth of energy consumption in the last two decades has caused the security of the domestic energy supply of buildings to face serious prob­lems.In this research,first by entering parameters such as the type of mate­rials,doors and windows,and the type of soil on the floor connected to the ground,etc.in the heat and cold load calculation software(HAP Carrier)as the design calculations and then in the second step entering the specifica­tions inferred from the Iran’s national building code as a reference for ener­gy saving calculations,calculations are performed and compared as the first criterion,and finally these two outputs are compared.The actual energy consumption and determination of the building energy consumption index are determined as another criterion,as well as the degree of deviation from the actual consumption.The results showed that the theoretical method and the thermal and refrigeration load calculations of the Zanjan Gas Company building have 6%difference in cooling load but the heating load is about 34%different,which means for cooling loads,the theoretical model can be used with high accuracy but for heating loads,the national building code needs fundamental changes.

Testing Operating Performance of Chinese Listed Firms before and after Cross-border M&As: The Role of Entrepreneurial Orientation

At a time when China encourages its firms to go overseas,especially to countries and regions involved in its"Belt and Road Initiative",and sets up a favorable domestic environment for innovation and entrepreneurship,this paper is a first trial looking along both the two dimensions to test whether Chinese firms’operating performance changes after cross-border merger and acquisition(CBM&A)activities,using entrepreneurial orientation(EO)as a moderating factor.The paper combines data from Chinese listed firms’annual reports,Chinese stock market financial statements database and the Zephyr database from 2001 to 2015 to examine how acquirers’operating performance changes after CBM&A activities using EO as a moderating factor.In order to test whether the results are affected by the stock market,this paper also defines abnormal return on equity(ROE)to detect abnormal operating performance.After these,the paper divides the sample into separate industry groups to see whether results will change.The results obtained for the whole sample show that the performance of Chinese listed firms is fluctuant after CBM&As within the sample years.It increases one year after the acquisition but drops two years later and then follows an increasing trend again.The moderating factor of EO is not significant for the sample as a whole.However,after dividing the sample into separate industry groups,it becomes clear that different industries have their own characteristics.EO helps Chinese listed firms to adjust to the post-acquisition situation and even to improve their performance to some extent in the metal mining industry and the business services industry.When ROE is substituted with abnormal ROE,the results do not change much.

Experimental investigation on operating behaviors of loop heat pipe with thermoelectric cooler under acceleration conditions

An experimental study was carried out in this article to investigate the transient operating performance of a Dual Compensation Chamber Loop Heat Pipe(DCCLHP) with Thermoelectric Cooler(TEC) under acceleration conditions and ammonia was selected as the working fluid.For the purpose of comparison, experimental work was conducted under terrestrial gravity.Sensitivity analysis was performed to explore the effect of several control parameters such as the heat load, acceleration magnitude and TEC assist on the startup and operating performance of the DCCLHP.Experimental results indicate that the DCCLHP can get to a steady-state operation when the heat load changes from 25 W to 300 W under terrestrial gravity.While under acceleration conditions, the DCCLHP can work at a high operating temperature or even fail to operate, which shows the acceleration effect plays a significant impact on the loop operation.The TEC assist with power of 10 W can improve the operating performance and reduce the operating temperature for the case of small heat load and acceleration magnitude.When the acceleration exceeds 3 g at large heat load, the effect of TEC assist on the operation at large heat load can be ignored.