基于单片机的"乒乓球"游戏机智能控制系统

单片机具有编程简单、易学、可靠性高、体积小等优点,广泛地应用于自动控制系统中.笔者设计利用AT89C2051单片机实现＂乒乓球＂智能游戏机系统,并且阐述了构成本系统的基本原理、硬件组成及相应的软件设计.     

嵌入式大容量数据采集系统设计

设计了一种基于AT91RM9200微处理器的工业监控现场嵌入式大容量数据采集系统,简化了现场设备层的布线难度,减小了现场设备模拟信号在传输过程中的衰减程度,为后期设备故障诊断和趋势预测提供了更为精确的数据信息。     

Experimental Design in the Optimization of a Microwave Acid Digestion Procedure of Biomorphic Ceramic Based on ZrO2

Abstract

The present work deals with the manufacturing of biomorphous ZrO₂-ceramics from oak wood as biological template structure. Oak wood was vacuum infiltrated with zirconia-sol. Subsequent pyrolysis in inert atmosphere at 800°C and annealing in air up to 1550°C resulted in the formation of porous, microcellular ZrO₂-ceramics. After the material characterization, we optimized the sample dissolution by acid attack in an oven under microwave irradiation. Experimental designs were used as a multivariate strategy for the effects evaluation of varying several variables. The optimization was performed using full factorial design 2⁴. Four variables (time, power, volume of HNO₃, and volume of HF) were considered as factors and as response the concentration of different metal ions in the optimization process.     

SELECTION OF A CATION EXCHANGE RESIN TO PRODUCE LACTIC ACID SOLUTIONS FROM WHEY FERMENTATION BROTHS

ABSTRACT

Lactic acid can be made by fermentation from inexpensive cheese whey. The acid is at present fairly costly, however, partly because of the costs of recovery and purification of the acid from the fementation broths. The present study has been undertaken to investigate a process that might reduce these costs. A number of commercial resins have been evaluated as ion exchangers for the production of lactic acid solutions. Amberlite IR-120, a gel strong cationic ion exchanger, was found to be the best resin. The loaded resin was regenerated efficiently. The results suggest that such a process is both technically and economically feasible.     

Acoustic Properties of Solid 4He in the Limit of Zero Impurity

We have studied the elasticity of solid ⁴He in relation with its possible supersolidity. For this we have measured acoustic resonance frequencies in a 1 cm³ cell filled either with polycrystals or with single crystals of ⁴He. We have observed a large stiffening at low temperature as first observed by Day and Beamish in polycrystals. The ³He impurity content has been varied from 300 ppb to 0.4 ppb. When kept in equilibrium with liquid helium, single crystals should be impurity free. In these crystals, a large stiffening is observed, which should not be the result of the pinning of dislocations by impurities.     

General-Purpose Situational Simulation Environment for Construction Education

The traditional construction education model based on precise well-defined problems and formal definitions is not satisfactorily fulfilling its mission of educating the decision makers of tomorrow. This realization has moved several researchers to explore alternatives where problem solving is carried out in conjunction with the environment, and concepts are embedded in the context promoting learning within the nexus of the activity. Several efforts have been undertaken to develop these environments resulting in a variety of special-purpose situational simulations. However, special-purpose situational simulations exhibit inherent limitations related to their application breadth, flexibility, and promotion of collaborations. These limitations cannot be resolved within the framework of special-purpose learning environments. A general-purpose environment is required to overcome these shortcomings and take full advantage of the situational learning paradigm. This paper describes the conceptual framework and pilot implementation of such an environment called the Virtual Coach.     

Chromium doping as a new approach to improve the cycling performance at high temperature of 5 V LiNi0.5Mn1.5O4-based positive electrode

LiCr_2YNi_0.5−YMn_1.5−YO₄ (0 < Y ≤ 0.2) spinels have been synthesized by a sucrose-aided combustion method. Two sets of Cr-doped samples have been obtained by heating the “as-prepared” samples at 700 and 900 °C for 1 h. X-ray diffraction and thermogravimetric data show that pure and single phase spinels with similar lattice parameter have been synthesized. The homogeneity and the sub-micrometric particle size of the spinels have been shown by SEM and TEM. The main effect of the temperature is to increase the particle size from ≈50 to ≈500 nm, on heating from 700 to 900 °C. The study of the influence of Cr-dopant content and thermal treatment on the electrochemical properties at 25 °C and at 55 °C has been carried out by galvanostatic cycling in Li-cells. The discharge capacity (≈130 mAh g⁻¹) does not noticeably change with the synthesis conditions; but the cycling performances are strongly modified. Key factors that control the cycling performances have been determined. The most highlighted result is that spinels heated at 900 °C with Y ≤ 0.1 have very high capacity retention at 55 °C (>96% after 40 cycles, cyclability >99.9% by cycle) indicating that metal doping is a new approach to prepare 5 V LiNi_0.5Mn_1.5O₅-based cathodes with excellent cycling performances at high temperature.     

Effects of B-ionizing radiation on the properties of flexible packaging materials

The influence of B-ionizing radiation on chemical structure and mass transfer phenomena was studied in the principal flexible food packaging materials (LDPE and OPP). No significant changes were observed in the structure of polymer matrices or in oxygen permeability and global migration after ionizing the materials at dose levels approved for food products ( < 110 kGy). Nevertheless, at low doses, it was observed that volatile organic compounds were present in ionized films. Several oxidation products were analysed by a dynamic head space technique. These oxidation products (typically ketones, aldehydes and carboxylic acids) could play a part in the organoleptic properties of prepackaged foods and, consequently, in their shelf-life.     

EXPLORATION AND EVALUATION OF THE ZUATA AREA, ORINOCO OIL BELT, VENEZUELA

Exploration activity in the Zuata area within the Orinoco Oil Belt in Venezuela has included the drilling of 161 wells and the recording of 3,000 km of seismic lines. Based on these results, a productive area of 9,200 sq. km has been defined, containing 79.3 B cu.m. (499 B brl)? of crude oil in-place, with densities ranging from 1.021 to 0.934 g/cu.cm (7–20 °API). The principal productive sands are of the Tertiary Officina Formation, deposited during a transgression which occurred in the Miocene. A distinctive feature of the productive formation is its progressive onlap against older rocks (Cretaceous, Paleozoic or Pre-Cambrian) in a southerly direction which, together with overlying shales, provide the trapping mechanism for the oil which migrated from the north. The productive sands were deposited in a fluvial to coastal plain with deltaic developments. The sands are unconsolidated and fine- to very coarse-grained, with an average porosity of 34% and a permeability of 7μm²(7D). The structure is a monocline dipping 0.5° to 2° to the NE, and the trapping mechanism is principally stratigraphic. In the 134 producers, 300 tests were completed which resulted in an average production of 25 cu.m/d (160 b/d) per well by beam pumping without dilution or heat. Subsequently, a steam cycle of 5,000 metric tons was injected into 16 wells; production increased to some 200 cu.m/d (1,250 b/d) per well. For future development, a Priority Area has been selected: this Area covers 3,500 sq kin, and contains 40.5 B cu.m (255 B brl) of crude oil with a density range of 1.014 to 0.993 g/cu.cm (8–11°API). The oil is at an average depth of 610 m, and the average net oil-sand thickness is 60 m. The oil-sand is generally divided into three zones separated by shales, and the gross productive thickness is some 110 m. Similar to Maraven ‘s experience in the oilfields of the Bolivar Coast in Western Venezuela, it may be expected that reservoir compaction will occur, and will be efficiently activated by steam-soak or “huff and puff’. Based on core compressibility measurements, a recovery factor from compaction drive and solution gas treatments could reach 12 % of the oil in-place. Under this premise, the Priority Area could have a potential recovery of 4.9 B cu. m. (30.6 B brl), which could support a production of 160,000 cu.m/d(1MM b/d) for 100 years. Any follow-up steam drive can be assumed to recover at least an additional 10% of the oil in-place. A Conceptual Development Plan based on clusters, inclined wells (due to the shallow depth) and steam soak has been proposed, and will be validated by a pilot test consisting of a seven-well cluster.