Measurement of number and size distribution of particles emitted from a mid-sized transportation multipoint port fuel injection gasoline engine

This study was carried out to characterize the engine-exhaust particulate emissions from a typical multipoint port fuel injection gasoline engine used in transportation sector. Though gasoline engine showed no visible tail pipe emissions yet its particle concentrations were comparable to mineral diesel, particularly at high engine loads. Average sizes of particles emitted in gasoline exhaust are found to be way smaller than particles emitted in diesel exhaust under similar operating conditions. The peak particle concentrations for mineral diesel never go below 40 nm size however for gasoline engine, it was as low as 20 nm for most engine operating conditions. Within a very limited operating range, gasoline engine performance was superior to its diesel counterparts in terms of particulate size and number distribution however it deteriorates very quickly as soon as the fuel-air mixture becomes closer to stoichiometric ratio, typically under high engine load and speed conditions.     

Study on the synthesis of a macroporous ethylacrylate‐divinylbenzene copolymer,its conversion into a bi‐functional cation exchange resin and applications for extraction of toxic heavy metals from wastewater

Macroporus ethylacrylate‐divinylbenzene copolymers were synthesized by suspension polymerization using diethyl phthalate and n‐heptane as diluent. A hydrolysis study revealed that conversion of esters into carboxylic acid groups was dependent on three factors: (1) crosslinkage: increases with a decrease in crosslinkage, (2) reagent: sulfuric acid>aqueous NaOH>NaOH in a 1 : 1 water to ethylene glycol, and (3) pore volume (PV): highest when PV was ～ 0.7 mL g^?1. Sulfuric acid hydrolyzed ester to ? COOH and introduced ? SO₃H on phenyl rings, thus producing a bi‐functional resin. The functional groups were verified by IR spectroscopy and quantified by acid–base titration. The bi‐functional resin's capacity for toxic heavy metals in water samples was 12.51, 10.43, 9.43, 13.21, and 11.12 mg g^?1 for Cu, Cd, Ni, Pb, and Zn, respectively and the recoveries exceeded >95% in range of pH 2–8, showing that it is suitable for water purification. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Experimental investigations of performance and emissions of Karanja oil and its blends in a single cylinder agricultural diesel engine

An experimental investigation has been carried out to analyze the performance and emission characteristics of a compression ignition engine fuelled with Karanja oil and its blends (10%, 20%, 50% and 75%) vis-a-vis mineral diesel. The effect of temperature on the viscosity of Karanja oil has also been investigated. Fuel preheating in the experiments – for reducing viscosity of Karanja oil and blends has been done by a specially designed heat exchanger, which utilizes waste heat from exhaust gases. A series of engine tests, with and without preheating/pre-conditioning have been conducted using each of the above fuel blends for comparative performance evaluation. The performance parameters evaluated include thermal efficiency, brake specific fuel consumption (BSFC), brake specific energy consumption (BSEC), and exhaust gas temperature whereas exhaust emissions include mass emissions of CO, HC, NO and smoke opacity. These parameters were evaluated in a single cylinder compression ignition engine typically used in agriculture sector of developing countries. The results of the experiment in each case were compared with baseline data of mineral diesel. Significant improvements have been observed in the performance parameters of the engine as well as exhaust emissions, when lower blends of Karanja oil were used with preheating and also without preheating. The gaseous emission of oxide of nitrogen from all blends with and with out preheating are lower than mineral diesel at all engine loads. Karanja oil blends with diesel (up to 50% v/v) without preheating as well as with preheating can replace diesel for operating the CI engines giving lower emissions and improved engine performance.     

Economics of Wind turbine as an energy fuel saver – A case study for remote application in oman

This paper presents a study carried out to investigate the economics of wind turbine as an energy fuel saver. The load and the wind data is taken from a remote agricultural research station in Oman. Presently, the station is provided with electricity from diesel-engine generating units. The annual peak load and minimum load recorded at the site is 130 kW and 28 kW respectively. The annual average wind speed at the site is 5.7 m/s. A 50-kW wind turbine is selected to demonstrate the economic feasibility of the turbine as a fuel saver. The results show that wind energy utilization is an attractive option with total specific cost of the selected wind turbine ranges between 7.4 and 8.45 ¢/kWh at 7.55% discount rate comparing to diesel generation operating cost of 14.3 ¢/kWh, considering the capital cost of diesel units as sunk. The simple payback period of the turbine is between 5.1 and 5.4 years and discounted payback between 6.7 and 8.0 years.     

Looking for surface states of ultra-cold neutrons

We report experiments testing the question whether or not ultra-cold neutrons (UCN) stored in traps with total-reflecting walls are temporarily adsorbed to the walls. A hypothetical process of sticking to the walls is theoretically intriguing but it can apparently make plausible the puzzling observations made in UCN storage experiments over the years.     

Neutron Structural Studies of the Superconducting (Nd1?yCay)Ba2(Cu0.94Ga0.06)3Oz System

We investigate the influence of Ca ions on the structural and superconducting properties of (Nd_1–y Cay)Ba₂(Cu_0.94Ga_0.06)₃O _z system by Rietveld refinement of the neutron diffraction patterns of three samples with y = 0.0 (A₁), y = 0.18 (A₂), and y = 0.36 (A₃) along with X-ray diffraction, resistivity, and ac susceptibility measurements. Samples A₂ and A₃ are superconducting with T _c values of 37 K and 76 K, respectively, whereas sample A₁ is semiconducting to 20 K. Neutron diffraction data confirms (a) the occurrence of a single-phase tetragonal structure (space group Pmmm) for all three samples; (b) Ca ions substitute at the Nd site; and (c) increasing y from 0.0 to 0.36 decreases Cu(1)-O(1), Cu(2)-O(2), and Nd-Cu(2) bond lengths, whereas Cu(2)-O(4) bond length increases with corresponding increase in T _c to 76 K due to increasing occupancy of Ca ions at Nd site. A correlation exists between the Cu(1)-O(1), Cu(2)-O(2), Cu(2)-O(4), and Nd-Cu(2) bond lengths and the measured T _c values of three samples.     

Investigations on corrosion resistance behavior in micro-milling of Ti-6Al-4V and Ti-6Al-7Nb alloy: a comparative study

Journal of Mechanical Science and Technology - We compared the corrosion resistance behavior of Ti-6Al-4V and Ti-6Al-7Nb alloy in micro-milling operation. The influence of parameters such as...     

基于差分非平稳Transformer的液压支架立柱压力预测

液压支架立柱压力预测是回采工艺决策的重要依据,也是确保围岩稳定的基础信息之一。然而,液压支架立柱压力虽然具有一定的规律性,却无法用简单的数学模型进行预测;且在回采过程中,支架不接顶、顶板破碎、传感器检测误差等带来大量的随机噪声,使得压力数据劣化为非平稳时间序列,给压力的预测带来的很大的困难。本文在Transformer基础上,提出一种差分非平稳Transformer模型,在Transformer的编码器和解码器中分别引入差分归一化和反归一化操作,以提升序列的平稳性。同时,在Transformer中采用去平稳注意力机制,计算序列元素之间的关联关系,以增强模型的预测能力。在真实的煤矿支架立柱数据集上的对比实验表明,本文提出的差分非平稳Transformer的预测效果达到0.674,表现明显优于LSTM、Transformer和非平稳Transformer模型。     

Application of maximum entropy principle in paralleled repairable systems

This paper investigates the application of the maximum entropy principle (MEP) to study the stochastic behavior of a repairable system. The system to be analyzed is a two-unit paralleled system whose failure rates are time-independent and whose repair time distribution is gamma. The exact distribution of some operating characteristics are compared with those obtained using MEP. Tables and graphs are provided.