A Study on How Urban Rail Operators Can Secure New Growth Engines for the Future Approach: The Case of Underground Urban Logistics System

Seoul Metro is Seoul’s leading metro company, transporting up to 3 billion people annually. However, future ridership is expected to plummet due to an aging and shrinking population with one of the fastest declining total fertility rates in the world. The COVID-19 pandemic in 2019 accelerated this phenomenon. On the contrary, the e-commerce and home delivery industries have developed significantly since COVID-19. Seoul’s current logistics infrastructure cannot handle it. Under the inflection point of declining passenger transportation demand and increasing urban logistics demand, urban rail operators need new growth engines. Therefore, it is necessary to consider the introduction of an UULS (underground urban logistics system) that transports parcels instead of passengers through urban railways. If the UULS becomes a reality, it can be expected to secure scarce logistics land in cities, protect the environment and prevent traffic congestion by operating eco-friendly mass urban transportation, and acquire new revenue sources for urban rail operators. The UULS’s B/C ratio is 1.32. The sensitivity analysis shows that the ratio is above 1 in most cases where the unit cost of transportation is not significantly reduced.

Evaluation of the Oxidation Reactivity and Behavior of Exhaust Soot Particles from Diesel Engines with Different Emission Levels

The aim of this study was to investigate the oxidation reactivity and behavior of exhaust particulate matter(PM)from diesel engines.PM samples from two diesel engines(1K,CY4102)with different emission levels were collected by a thermophoretic system and a quartz filter.The oxidation reactivity,oxidation behaviors,and physicochemical properties of the PM samples were analyzed using thermogravimetric analysis(TGA),high-resolution transmission electron microscopy(HRTEM),Fourier-transform infrared spectrometry(FTIR),and Raman spectroscopy.The results showed that there was a great difference in the oxidation reactivity of soot particles emitted by the two different diesel engines.A qualitative analysis of the factors influencing oxidation reactivity showed that the nanostructure,degree of graphitization,and relative concentration of aliphatic C—H functional groups were the most important factors,whereas no significant correlation was found between the primary particle size and activation energy of the diesel soot.Based on the oxidation behavior analysis,the diesel soot particles exhibited both internal and surface oxidation modes during the oxidation process.Surface oxidation was dominant during the initial stage,and as oxidation progressed,the mode gradually changed to internal oxidation.Internal oxidation mode of soot particles from the 1K engine was significantly higher than that of CY4102.

Performance, Combustion and Emission Characteristics of Oxygenated Diesel in DI Engines: A Critical Review

The transition from non-renewable to renewable energy sources is a significant challenge of our time. In the fuel industry, oxygenated additives such as butanol are transforming conventional fuels into renewable biofuels. This technology has been utilized in reciprocating engines for decades. This paper reviews the viability of using an n-butanol blend as a short-term replacement for diesel by analyzing its physical and chemical properties, combustion, performance, and emission characteristics in compression ignition (CI) engines under various conditions, including variable load, speed, acceleration, and both stationary and transient cycles. N-Butanol exhibits higher viscosity, better lubricity, higher heating value, improved blend stability, enhanced cold-flow properties, and higher density. These factors influence spray formation, injection timing, atomization, and combustion characteristics. Its higher oxygen content improves the diffusion combustion stage and efficiency. Adding 5% and 10% n-butanol to diesel increases pressure and apparent heat release rate, slightly reduces temperature, and improves thermal efficiency, with mixed effects on CO and THC emissions and a notable decrease in particulate matter emissions. Fuel consumption increases, while the impact on NOx emissions varies. A 10% butanol blend is considered optimal for enhancing performance and reducing particulate emissions without significantly affecting NOx emissions. Blending up to 40% butanol with diesel does not require engine modifications or ECU recalibrations in engines calibrated for pure diesel. Due to its advantageous properties and performance, n-butanol is recommended as a superior alcohol-diesel blend than ethanol for short-term diesel replacement.

Performance optimization on finite-time quantum Carnot engines and refrigerators based on spin-1/2 systems driven by a squeezed reservoir

We investigate the finite-time performance of a quantum endoreversible Carnot engine cycle and its inverse operation-Carnot refrigeration cycle,employing a spin-1/2 system as the working substance.The thermal machine is alternatively driven by a hot boson bath of inverse temperatureβ_(h)and a cold boson bath at inverse temperatureβ_(c)(>βh).While for the engine model the hot bath is constructed to be squeezed,in the refrigeration cycle the cold bath is established to be squeezed,with squeezing parameter r.We obtain the analytical expressions for both efficiency and power in heat engines and for coefficient of performance and cooling rate in refrigerators.We find that,in the high-temperature limit,the efficiency at maximum power is bounded by the analytical valueη_(+)=√sech(2r)(1-η_(C)),and the coefficient of performance at the maximum figure of merit is limited byε_(+)=√sech(2r)(1+ε_(C))/sech(2r)(1+ε_(C))-εC)-1,whereη_(C)=1-β_(h)/β_(c)andε_(C)=β_(h)/(β_(c)-β_(h))are the respective Carnot values of the engines and refrigerators.These analytical results are identical to those obtained from the Carnot engines based on harmonic systems,indicating that the efficiency at maximum power and coefficient at maximum figure of merit are independent of the working substance.

基于Artificial Engines的三维交通仿真系统的设计

三维交通仿真是对可视化交通管理系统进行分析和评价的一个有效方法,也是智能交通系统的一个重要研究方向.本文使用Artificial Engines这种托管3D引擎技术,通过由道路数据自动生成大规模三维路网场景,以及车辆运动算法,建立起一种可视化、实时高效的三维交通管理系统.

Optimization of combined endoreversible Carnot heat engines with different objectives

Taking the output power, thermal efficiency, and thermo-economic performance as the optimization objectives, we optimize the operation parameters of a thermodynamic system with combined endoreversible Carnot heat engines in this paper. The applicabilities of the entropy generation minimization and entransy theory to the optimizations are discussed. For the discussed cases, only the entransy loss coefficient is always agreeable to the optimization of thermal efficiency. The applicabilities of the other discussed concepts to the optimizations are conditional. Different concepts and principles are needed for different optimization objectives, and the optimization principles have their application preconditions. When the preconditions are not satisfied, the principles may be not applicable.

Current Application of Search Engines and Their Developing Trend

FAN Xiao-wen School of Pharmacy, Shenyang Pharmaceutical University, Shenyang,110016The basic types of current search engines which can help users to perfume laborious information-gathering tasks on Internet is proposed. Basically, the search engines can be classified into index engine, directory engine and agent engine on WWW information service. The key technologies of web mine, automatic classifying of documents and ordering regulation of feedback information are discussed. Finally, the developing trend of search engines is pointed out by analyzing their practical application on World Wide Web.

Novel Oxygen Storage Components Promoted Palladium Catalysts for Emission Control in Natural Gas Powered Engines

A three-way catalyst comprised novel oxygen storage components for emission control in natural gas powered engines was prepared. The addition of novel oxygen storage components to the Pd/γ-Al2O3 catalysts resulted in improved activities of the fresh and aged catalyst by lowering the light-off temperature for methane in natural gas engines exhaust.

Ensemble Recurrent Neural Network-Based Residual Useful Life Prognostics of Aircraft Engines

Residual useful life(RUL)prediction is a key issue for improving efficiency of aircraft engines and reducing their maintenance cost.Owing to various failure mechanism and operating environment,the application of classical models in RUL prediction of aircraft engines is fairly difficult.In this study,a novel RUL prognostics method based on using ensemble recurrent neural network to process massive sensor data is proposed.First of all,sensor data obtained from the aircraft engines are preprocessed to eliminate singular values,reduce random fluctuation and preserve degradation trend of the raw sensor data.Secondly,three kinds of recurrent neural networks(RNN),including ordinary RNN,long shortterm memory(LSTM),and gated recurrent unit(GRU),are individually constructed.Thirdly,ensemble learning mechanism is designed to merge the above RNNs for producing a more accurate RUL prediction.The effectiveness of the proposed method is validated using two characteristically different turbofan engine datasets.Experimental results show a competitive performance of the proposed method in comparison with typical methods reported in literatures.

Fault Identification and Health Monitoring of Gas Turbine Engines Using Hybrid Machine Learning-based Strategies

Ahealth monitoring scheme is developed in this work by using hybrid machine learning strategies to iden-tify the fault severity and assess the health status of the aircraft gas turbine engine that is subject to component degrada-tions that are caused by fouling and erosion.The proposed hybrid framework involves integrating both supervised recur-rent neural networks and unsupervised self-organizing maps methodologies,where the former is developed to extract ef-fective features that can be associated with the engine health condition and the latter is constructed for fault severity modeling and tracking of each considered degradation mode.Advantages of our proposed methodology are that it ac-complishes fault identification and health monitoring objectives by only discovering inherent health information that are available in the system I/O data at each operating point.The effectiveness of our approach is validated and justified with engine data under various degradation modes in compressors and turbines.

Life cycle of remanufactured engines

The life cycle index of remanufactured engines was assessed by using the method of life cycle assessment （LCA）. A remanufactured engine of a certain domestic brand was taken as researching object. Engine reproducing engineering was investigated from three aspects which were energy, material and environment. The application of LCA on remanufacturing engines was discussed in detail with a practical case. The results indicate that remanufacturing an engine can save 55kg steels, 8.3kg aluminum and 113kW·h electric powers and reduce emissions of 565kg CO2, 6.09kg CO, 1.01kg NOx, 3.985kg SOx and 288.725kg solid waste. The remanufacturing of engines possesses great economic value and practicability.

Search for Effective Catalysts for the Development of Engines Based on the Products of Catalytic Decomposition of N_(2)O

The paper presents requirements for the N_(2)O decomposition catalyst and provides justification for the selection of components to develop its formulation.The methods to study the physical and chemical as well as catalytic properties of catalysts were developed,and the results of experimental studies on the properties of catalysts with different composition in the laboratory conditions were presented.The activity of samples of compact metal catalysts as well as samples of supported metal and oxide catalysts in the nitrous oxide decomposition reaction was studies.The methodology for determining the activity of catalysts in the decomposition reaction of N_(2)O is presented,as well as the design of an experimental reactor for determining the activity of the catalyst by the minimum temperature for the onset of the decomposition reaction of N_(2)O.In the course of the study,the following series of catalyst activity are determined in the N_(2)O decomposition reaction up to a temperature of 600℃:based on platinum group metals applied to the aluminum oxide carrier-Rh>Ru>Ir>Pt>Pd;based on simple oxides applied to the aluminum oxide carrier-CoO>Cr_(2)O_(3),MnO_(2)>CuO>ZrO_(2)>NiO>Fe_(2)O_(3).The following activity series for the most promising carriers are also determined:by the onset temperature of decomposition,ZrO_(2)>Al_(2)O_(3)-CaO>Al_(2)O_(3)-ZrO_(2)>Al_(2)O_(3)-AlN>θ-Al_(2)O_(3)>Al_(2)O_(3)-SiO_(2)>SiO_(2)>α-Al_(2)O_(3);by the rate constants of N_(2)O decomposition,Al_(2)O_(3)-SiO_(2)>Al_(2)O_(3)-AlN>ZrO_(2)>Al_(2)O_(3)>Al_(2)O_(3)-ZrO_(2)>Al_(2)O_(3)-CaO>α-Al_(2)O_(3)>SiO_(2).The paper presents the results of selecting the active component and carriers for the supported catalyst.The author proposes formulations of the nitrous oxide decomposition catalyst for bench testing in simulated engines.

Editorial for the Special Issue on Engines and Fuels

Internal combustion engines (ICEs) have made tremendous contributions to the economic and social development of every country in the world. Today, the main aim of ICE development is to further improve thermal efficiency and reduce carbon emissions. With the rapid development of energy-saving technologies, academia and the industrial community are paying a great deal of attention to a crop of disruptive ICE technologies. The Chinese Academy of Engineering (CAE) held the International Summit on Breakout Technology of Engines and Fuels to discuss this development trend along with potential breakout technologies.

Monolithic Catalysts with Low Noble-Metal Content for Exhaust Purification of Small Gasoline Engines

A series of low noble-metal coment monolithic catalysts for exhaust purification of small gasoline engines was investigated, and it was found that the Pt/Rh-OSM/Al2O3 （where OSM was oxygen storage material） catalyst with Ce0.5Zr0.5-MnOx（3%MnOx） OSM held low light-off temperature for CO, HC, and NO; quite wide three-way window, and outstanding thermal stability. The catalyst could efficiently comrol exhaust emission of small gasoline engines.

Prospects of Reciprocating Engines and Fuels

Reciprocating engines and their fuels are largely associated with road transport. This isn’t surprising. About 70% of transport-sector greenhouse gas emissions today are from road vehicles [1], and these vehicles are overwhelmingly propelled by reciprocating engines. However, reciprocating engines are also widely used in other sectors, particularly off-road land transport, sea transport, and electrical power generation.

Evaluation and Control of Cyclic Variation in Spark Ignited Engines by a Thermodynamic Model

An evaluation method of engine cyclic variation is proposed based on fuzzy mathematics concept. The degree of engine cyclic variation is divided into 4 levels: stable, slight variation, moderate variation and serious variation based on the statistic standard deviation of residual gas temperatures within the specified simulation cycles and the function of cyclic variation is also inducted for the cyclic variation control. Because the degree of engine cyclic variation can be estimated qualitatively, the effective control means can be applied to appease the undesired cyclic variation. Simulation result shows that for a very serious cyclic variation through the proper adjustment of the spark angle and the cyclic variation will disappear.

Optimization of Transducer Location for Novel Non-Intrusive Methodologies of Diagnosis in Diesel Engines

The health monitoring has been studied to ensure integrity of design of engine structure by detection,quantification,and prediction of damages.Early detection of faults may allow the downtime of maintenance to be rescheduled,thus preventing sudden shutdown of machines.In cylinder pressure developed,vibrations and noise emissions data provide a rich source of information about condition of engines.Monitoring of vibrations and noise emissions are novel non-intrusive methodologies for which positioning of various transducers are important issue.The presented work shows applicability of these diagnosis methodologies adopted in case of diesel engines.The effects of changing various fuel injection parameters was analyzed.Scope of using non-intrusive technique has been analyzed by changing locations of microphone.Novelty of this worklies in exploring signal processing methods for various locations around the engine test set up.Various frequency ranges of contributing noise and vibration sources were identified.Time-Frequency analysis showed the onset of various cyclic.Based on the identification of various frequency bands,it is possible to device suitable filters in order to extract more information.

NUMERICAL MODELING OF TURBULENTEVAPORATING GAS-DROPLET TWO-PHASE FLOWS IN AN AFTERBURNER DIFFUSOR OF TURBO-FAN JET ENGINES

The two-dimensional turbulent evaporating gas-droplet two-phase flows in an afterburner diffusor of turbo-fan jet engines are simulated by the k-ε turbulence model and the particle trajectory model. Comparison of predicted gas velocity and temperature distributions with experimental results for the cases without liquid spray shows pretty good agreement. Gas-droplet two-phase flow predictions give plausible droplet trajectories, fuel-vapor concentration distribution, gas-phase velocity and temperature field in presence of liquid droplets. One run of computation with this method is made for a particular afterburner. The results indicate that the location of the atomizers is not favorable to flame stabilization and combustion efficiency. The proposed numerical modeling can also be adopted for optimization design and performance evaluation of afterburner combustors of turbo-fan jet engines.

SURGE FORECAST FOR AERONAUTICAL ENGINES WITH EXTENDED KALMAN ESTIMATION

Abstract In this paper,the theory of extended Kalman estimation is applied to state estimate ofcompression system, for which a nonlinear model is developed by Greitzer.A criterion ofdetermining whether surge will occur in a turbine engine is presented.The combination ofstate estimation and the criterion of determining surge forms a surge prediction algorithm,which is the theoretical basis of designing a surge indicator for the turbine engine.

Reliability Based Multi-Objective Thermodynamic Cycle Optimisation of Turbofan Engines Using Luus-Jaakola Algorithm

Aircraft engine design is a complicated process,as it involves huge number of components.The design process begins with parametric cycle analysis.It is crucial to determine the optimum values of the cycle parameters that would give a robust design in the early phase of engine development,to shorten the design cycle for cost saving and man-hour reduction.To obtain a robust solution,optimisation program is often being executed more than once,especially in Reliability Based Design Optimisations(RBDO)with Monte-Carlo Simulation(MCS)scheme for complex systems which require thousands to millions of optimisation loops to be executed.This paper presents a fast heuristic technique to optimise the thermodynamic cycle of two-spool separated flow turbofan engines based on energy and probability of failure criteria based on Luus-Jaakola algorithm(LJ).A computer program called Turbo Jet Engine Optimiser v2.0(TJEO-2.0)has been developed to perform the optimisation calculation.The program is made up of inner and outer loops,where LJ is used in the outer loop to determine the design variables while parametric cycle analysis of the engine is done in the inner loop to determine the engine performance.Latin-Hypercube-Sampling(LHS)technique is used to sample the design and model variations for uncertainty analysis.The results show that optimisation without reliability criteria may lead to high probability of failure of more than 11%on average.The thrust obtained with uncertainty quantification was about 25%higher than the one without uncertainty quantification,at the expense of less than 3%of fuel consumption.The proposed algorithm can solve the turbofan RBDO problem within 3 min.