COLOR VISION SYSTEM FOR RIPENESS INSPECTION OF OIL PALM ELAEIS GUINEENSIS

In checking harvesting discipline and quality control for oil palm fruits, color has presumably been an important guide to whether the oil content has reached a maximum where the fruit bunch is ready for cutting. However, establishing a single and harmonious standard base on color is a very contentious issue in the oil palm industry because of the subjective nature of the human vision of color. This was further complicated due to the lack of information on fruit color upon which to base a definite ripeness criterion. We demonstrated in this paper that this problem can be solved using machine vision technology. Methods used were to treat color in HSI (Hue, Saturation and Intensity) color space and applied multivariate discriminant analysis. These have proven to be highly effective for color evaluation and image processing. The vision system was trained to classify oil palms into four quality grades according to PORIM (Palm Oil Research Institute of Malaysia) inspection standards. These are the unripe, the underripe, the optimally ripe and the overripe classes. Depending upon the quality feature evaluated, misclassification by the vision system varied from 5 to 12% but averaged at about 8%. Machine vision disagreement ranged from 2 to 19%.     

比较CypherTM和TaxusTM支架在冠心病合并糖尿病患者中应用的安全性和有效性

背景与裸支架相比,药物洗脱支架可以显著降低冠心病合并糖尿病患者PCI术后再狭窄率和靶病变重建率.但目前尚未见关于直接比较雷帕霉素洗脱支架(CypherTM)和紫杉醇洗脱支架(TaxusTM)在治疗冠心病合并糖尿病患者中安全性和有效性的研究.目的观察和比较两种药物洗脱支架在冠心病合并糖尿病患者中应用的安全性和有效性.方法自2002年6月～2004年2月新加坡国立大学医院心脏中心所有置入Cypher或Taxus支架冠心病合并糖尿病患者,观察:术后6个月的主要不良心脏事件(包括死亡、心肌梗死、靶病变重建).结果     

General pole restriction controller design

Pole-assignment controller design suffers from the disadvantage that the prescribed pole locations may not be a suitable choice when the dynamics of the process are changing. A general design method that restricts the closed-loop poles to be within a certain desired region specified by engineering judgement, instead of fixing the poles in a prescribed location, is presented. The method can be used for regulating a process with time delay, non-minimum zero-phase behaviour, and open-loop unstable characteristics.     

电镀锌钢材表面物理气相沉积Zn-Mg合金镀层的电化学性能(英文)

锌合金镀层由于具有较强的耐腐蚀性能而得到广泛的关注,特别是Zn-Mg合金镀层,其耐腐蚀性能能得到显著提高。采用气相沉积方法制备不同镁含量的Zn-Mg合金镀层,研究Zn-Mg合金镀层中镁含量对其耐腐蚀性能的影响。在3%NaCl溶液中进行浸泡试验、动电位测试和电偶腐蚀试验,研究不同Mg含量镀层的耐腐蚀性能。结果表明,Zn-Mg合金镀层的耐腐蚀性能与Mg含量显著相关,镀层的腐蚀电位随着Mg含量的增加而降低,但是腐蚀电流密度却升高,直至15%Mg含量;在Zn-Mg合金镀层中存在钝化区。     

Transient current spectroscopy and frequency dispersion studies of low temperature GaAs and Al0.3Ga0.7As metal-insulator-semiconductor diodes

Low temperature (LT)-grown GaAs and Al_0.3Ga_0.7As metal-insulator-n⁺-GaAs (MIN) diodes have been fabricated and their electrical properties analyzed. Studies were carried out to evaluate the interfacial quality of the LT layer and the underlying n⁺-GaAs layer using transient current spectroscopy (TCS) and capacitance-frequency (C-f) characterization. TCS studies on LT-GaAs revealed a high concentration of a continuum of states anda dominant electron trap with an activation energy of 0.52eV. In LT-Al_0.3Ga_0.7As, a shallow trap at 0.36eV and two deep level traps at 0.85eV and 1.12eV were observed. Frequency dispersion was observed to be less for LT-GaAs samples with an AlAs barrier layer than without an AlAs barrier layer. However, LT-Al_0.3Ga_0.7As MIN diodes displayed a smaller frequency dispersion than LT-GaAs MIN diodes. Upon further investigation into MISFET devices, it was found that LT-Al_0.3Ga_0.7As MISFET devices had better transconductance frequency dispersion characteristics than LT-GaAs MISFET devices did.     

Stability and robustness analysis of boundary control of a flexible space structure

We consider the question of the robustness of boundary control for a simplified SCOLE (spacecraft control laboratory experiment) model. A continuum model consisting of a long flexible mast joining two rigid bodies, one of which represents the space shuttle orbiter, the other an antenna reflector, is developed. The dynamics of the system are represented by a coupled set of ordinary and partial differential equations, and formulated as a wave equation in a Hilbert space by using a semigroup approach. For a continuum, distributed controls have often been proposed to stabilize the perturbed system. However, distributed controls for the continuous system are not practical to implement. Hence, for easy implementation we employ the boundary controls, as a special class of localized controls, that are control forces or torques applied only at the boundary. In this paper it is shown that the flexible system subject to a certain class of perturbations remains stabilizable by the same boundary feedback control as that for the nominal system. The results of numerical simulations for the simplified model are also presented to demonstrate the effective strong stabilization and robustness of the boundary controller with respect to the various perturbations.     

COMPARISON OF TRANSESTERIFIED PALM STEARIN/SUNFLOWER OIL BLENDS CATALYZED BY PSEUDOMONAS AND MUCOR JAVANICUS LIPASE

Palm stearin and sunflower oil mixtures in three different ratio of 3:7, 5:5 and 7:3 (w/w) were subjected to transesterification catalyzed by immobilized lipases from Pseudomonas and Mucor javanicus in a solvent-free system. The ability of these lipases to alter the physical properties of the fat blends was studied. Slip melting point (SMP), differential scanning calorimetry and X-ray diffraction analyses were used to evaluate the physical properties of the transesterified blends. The percentage of free fatty acids liberated was also determined. Results indicated that the Pseudomonas lipase was catalytically more active than Mucor javanicus lipase as shown by marked changes in the triacylglycerol profile and fatty acids released. Pseudomonas lipase-catalyzed mixtures also showed a bigger drop in SMP and successfully changed the polymorphic form from the dominant β crystal form in control blends to β'crystal form in the transesterified mixtures.     

Analysis of coatings which inhibit epoxy bleeding in electronic packaging

The bleeding of epoxy resin around surfaces, undergoing bonding in electronic packaging assembly, has for long caused sporadic yield-loss. This loss is more severe in advanced and dense packages. Previously it has been supposed that the loss results from surface contaminants which are reduced by vacuum bakeout. In fact, that procedure generates coatings of hydrocarbons as we show by surface analysis. The coatings very strongly affect the wettabilities and measured surface energies of substrates. In particular, the comparatively low surface energy of hydrocarbon films on gold surfaces shows how the surfaces can be engineered, with coatings of “appropriate cleanliness”, to systematically inhibit epoxy bleeding. This revised version was published online in July 2006 with corrections to the Cover Date.     

春之路

这个纪念方案拟建一条道路,以表达对2008年5·12四川大地震遇难者的沉痛哀悼.这条路毗邻四川省的某一河边,那里有一大片可循环利用的建筑废墟地,零星分布着小麦田.独特的场所体验由地下和地上两个项目组成.