THE IMPROVEMENT OF PERFORMANCE IN PARALLEL-PLATE HEAT EXCHANGERS BY INSERTING DM PARALLEL AN IMPERMEABLE SHEET FOR DOUBLE-PASS OPERATIONS

Considerable improvement of heat transfer in flat-plate heat exchangers is obtainable by inserting in parallel an impermeable, resistless sheet to divide an open duct into two channels for double-flow operations. The effect of impermeable-sheet location on the enhancement of transfer efficiency as well as on the increment of power consumption, has been discussion.     

Perceptron Learning in Engineering Design

A model of machine learning in engineering design is presented based on the concept of self-adjustment of internal control parameters and perceptron. A perceptron is defined as a four-tuple entity which can answer either "yes" or "no" in the problem domain. The problem of structural design is cast in a form that can be described by a perceptron without hidden units. Some results from our experimentation are presented in tabular form. The paper is concluded by a comparison of perceptron and explanation-based learning.     

FUNCTIONS OF STARCH IN FORMATION OF STARCH/MEAT COMPOSITE DURING HEATING

The functions of three starches (potato, corn, and rice) on the formation of starch and pork ham batter composite during heating were investigated. Thermal properties were measured by differential scanning calorimetry (DSC) and rheological characteristics were determined by small amplitude oscillatory shearing. DSC thermograms did not show any chemical interactions between starch and meat protein during heating. The dramatic increase in G' and G" of starch/meat composite appeared to be associated with the gelatinization of starch. The microstructures of pork ham batter, starch, and starch/meat composites were revealed by both scanning electron microscopy and light microscopy.     

Shearing interference microscope for step‐height measurements

A shearing interference microscope using a Savart prism as the shear plate is proposed for inspecting step‐heights. Where the light beam propagates through the Savart prism and microscopic system to illuminate the sample, it then turns back to re‐pass through the Savart prism and microscopic system to generate a shearing interference pattern on the camera. Two measurement modes, phase‐shifting and phase‐scanning, can be utilized to determine the depths of the step‐heights on the sample. The first mode, which employs a narrowband source, is based on the five‐step phase‐shifting algorithm and has a measurement range of a quarter‐wavelength. The second mode, which adopts a broadband source, is based on peak‐intensity identification technology and has a measurement range up to a few micrometres. This paper is to introduce the configuration and measurement theory of this microscope, perform a setup used to implement it, and present the experimental results from the uses of the setup. The results not only verify the validity but also confirm the high measurement repeatability of the proposed microscope.     

THE PHASE TRANSFORMATION OF δ-FERRITE IN A STRUCTURALLY DUPLEX IRON-ALUMINIUM-MANGANESE-MOLYBDENUM ALLOY

成分为0.07％C,4.6％Al,32.5％Mn,3.1％Mo的Fe-Al-Mn-Mo合金,于1100℃固溶处理后,具有γ+δ复相组织。用金相法研究了δ铁素体于950—450℃温度范围的组织转变过程,并对转变产物进行了结构与成分的相分析。以金相法测定了等温转变的开始动力学曲线,测量了等温转变过程中δ铁素体内显微硬度的变化。 研究表明:于950—750℃有δ→γ转变,650—550℃有δ→γ+M_(23)C_6转变。此二转变分别以完全扩散型及贝茵体型方式在相应的温度范围内同时进行。750—450℃有α-Mn型晶体结构的金属化合物X相宜δ铁素体中脱溶。X相平均化学式为Fe_(26)Mn_(16)Mo_8Al_8。     

Additional properties of an extended maximum principle†

This paper establishes conditions of optimality for linear systems whoso control functions are quantized either in magnitude or in switching instants, or both. Optimization of such systems hitherto has been limited primarily to dynamic programming techniques and direct enumeration. The results are derived from the total variations of the cost functional. The main theorem provides sufficient conditions of optimality for linear systems with quadratic and positive semi-definite performance index. The results are significant for digital control systems, pulse-code-modulated control systems and some types of pulse-frequency-modulated systems which are subject to quantized variations only. For the special case where the control functions are not quantized, the optimality conditions provided by the extended maximum principle are shown to be necessary and sufficient.     

THERMAL DIFFUSION IN SPIRAL WIRED COLUMNS WITH TRANSVERSE SAMPLING STREAMS

The equations that may be employed to predict the optimum wire angles of inclination for performance in a concentric-tube thermal-diffusion column with a tight-fitting wire spiral, having a diameter equal to the annular spacing, wrapped on the entire inner tube, and operating with transverse sampling streams, have been derived. Considerable improvement in performance is obtainable if the wire angle is adjusted at the optimum angle, instead of the absence of a wire spiral, so that the convection strength can be properly reduced and controlled, resulting in suppressing the undesirable remixing effect while still preserving the desirable cascading effect. Accordingly, essential savings in fixed charges and operating expense can be achieved, particularly for lower production rate operations or for a smaller degree of separation.     

THE SEPARATION OF ISOPROPYL ETHER FROM METHYL ETHYL KETONE BY EXTRACTIVE DISTILLATION

Isopropyl ether (IPE) cannot be completely separated from its mixtures with methyl ethyl ketone (MEK) by distillation because of the presence of the minimum binary azeotrope. However these two can be readily separated by using extractive distillation in which the extractive distillation agent is a higher boiling oxygenated, nitrogenous and/or sulfur containing organic compound or a mixture of these. Typical examples of effective agents are: ethylene carbonate; adiponitrile and 1,4-butanediol; sulfolane, dimethyl-sulfoxide (DMSO) and triethylene glycol.     

Porous Cube-like In2O3 Nanoparticles and Their Sensing Characteristics toward Ethanol

Porous cube-like crystalline In2O3 nanoparticles with an average diagonal length of 34.8 nm were fabricated by a laser ablation-reflux process to form In（OH）3, followed by a calcination treatment to yield porous In2O3. HRTEM （high-resolution transmission electronic microscopy）, XRD （X-ray diffraction）, BET （Brunauer-Emmett-Teller）, and XPS （X-ray photoelectron spectroscopy） analysis were used to characterize their crystalline structures, grain sizes, surface areas, and surface compositions. The as-prepared porous in-dium oxides were tested for their sensing properties toward ethanol. Non-porous In2O3 nanopowder （about 40 nm） was also examined in order to compare the results with the as-prepared porous In2O3 nanomaterials. The porous In2O3 exhibited much better performance than that of non-porosus In2O3, and showed enhanced sensitivity with a lower detection limit than other reported In2O3-based materials when exposed to ethanol. Good gas sensitivity and linear behavior as a function of ethanol concentration were observed in the porous In2O3 nanoparticles.     

Effect of screw profile on extrusion-cooking of wheat flour by a twin-screw extruder

The effects of forward-, reverse-, and no-flight screw elements on the residence time distribution, dispersion number, and product properties were investigated in extrusion cooking of wheat flours in a twin-screw extruder. Mean residence times of 46.5s with a forward element increased to 59.6s with a reverse flight and 67.6s with a no-flight element. Dispersion numbers were 0.051, 0.056, and 0.075 respectively. The no-flight element reduced cooking loss and increased the degree of gelatinization of products.