Maturity determination of fresh dates by near infrared spectrometry

In Israel, fresh dates are normally harvested unripe and stored in a controlled environment until marketed. Proper ripening depends on maturity at harvest time. Sugar and water contents of the dates are considered important maturity attributes. Decision‐making on the harvesting schedule for each section in a plantation of fresh dates (variety Hayani) is one of the major problems for the growers. In order to estimate the optimum harvest time, conventional laboratory methods have been used to assess the maturity of samples of dates; methods which by nature are destructive, manual and time consuming. A semi‐automatic system for maturity determination of fresh dates has been developed, tested and operated. It combines a near infrared (NIR) spectrometer with a step‐wise cell conveyor, both of which are controlled by a PC. The NIR models were based on measuring the water and total soluble solids (TSS) contents. The calibration models and the prediction results had a standard error of prediction (SEP) of 1% for TSS and water contents. The correlation coefficient R between TSS and water contents as predicted by NIR models and as measured in routine laboratory destructive tests was 0.9. The system was capable of testing 100 dates in 3 min. © 1999 Society of Chemical Industry     

Computational limitations of model-based recognition

Reliable object recognition is an essential part of most visual systems. Model-based approaches to object recognition use a database (a library) of modeled objects; for a given set of sensed data, the problem of model-based recognition is to identify and locate the objects from the library that are present in the data. We show that the complexity of model-based recognition depends very heavily on the number of object models in the library even if each object is modeled by a small number of discrete features. Specifically, deciding whether a discrete set of sensed data can be interpreted as transformed object models from a given library is NP-complete if the transformation is any combination of translation, rotation, scaling, and perspective projection. This suggests that efficient algorithms for model-based recognition must use additional structure to avoid the inherent computational difficulties. © 1998 John Wiley & Sons, Inc.     

Re-Examination of the Bread Firming Curve

Bread firming curves are generally accepted to be continuous, positively sloped, and convex at all points. However, a review of published literature suggests this may not always be so. To investigate possible deviations from the assumed curve, a dynamic rheometry method was developed and used to measure firmness every 12h for at least 10 days. It was non-destructive so eliminating sample variance. An interpretation of the results is as follows. The firming of each of four adjacent slices from a 1-pound loaf showed random fluctuations, independent of adjacent slices and forming a discontinuous curve. They were analogous to quantum peaps of an electron between orbitals. Accordingly, averaging firming of the four slices was inappropriate, because fluctuations in firmness were discreet and not necessarily due to random error. Additionally, softening to a lower level and subsequent refirming to the previous higher level indidcated structural collapse and recovery. Less frequently, these quasi-quantum leaps were upward, followed by collapse to the more prevalent trend. This binary random fluctuation, or BINARF, was interpreted as showing two possible independent firming mechanisms. These might be (1) hydrogen bonding and/or hydrophobic bonding between starch and gluten and (2) starch retrogradation.     

Treated Oil Shale Ashes as a Substitute for Natural Aggregates,Sand, and Cement in Concrete

Oil shales are rocks that contain organic matter and are used as a low-grade fuel for energy production. The oil shale combustion process produces large quantities of ash as combustion wastes. These residues contain a high concentration of calcium anhydrite (CaSO₄) and calcium carbonate (CaCO₃), which can be utilized to neutralize acidic wastes (e. g., wastes from the phosphate industry) .Using untreated oil shale bottom ash as partial substitutes for aggregates, natural sand, and cement in concrete mixtures has resulted in a significantly decreased performance of the concrete mixtures. However, by blending the oil shale with acidic materials, the concrete properties improved, as manifested by the development of compressive strength and the workability of the concrete mixtures. In the current study, it was shown that treatment of the oil shale ash with the acidic waste of the Israeli phosphate industry or with phosphoric acid significantly improves the properties of the concrete mixtures, by partial replacement of the natural aggregates and sand by the treated oil shale ash.     

非接触式钢轨平直度及扭曲度测量研究

为了对钢轨厂生产的成品钢轨外表面轮廓进行全面的检测,设计了一种非接触式钢轨轮廓检测系统。该系统基于激光轮廓仪和高精度位移传感器采集到的钢轨轮廓数据,使用弦测法及移动平均平滑滤波计算钢轨的平直度,使用共面法计算钢轨扭曲度,完成钢轨轮廓数据的检测。试验表明,系统测量的标准差为20μm以内,与标准测量方法所得结果对比误差均在合理范围内,该系统能够准确且稳定地完成对钢轨平直度和扭曲度的测量。     

Compact Labeling Scheme for XML Ancestor Queries

XML documents are often viewed as trees (basically the parse tree of the document), and queries over such documents typically test for ancestor relationships among tree nodes. Search engines process such queries using an index structure summarizing the ancestor relations. In the index, each document item (tree node) is identified using some logical id (node label), such that, given two labels, the engine can determine the ancestor relationship between the corresponding nodes. The length of the labels is a main factor of the index size. Therefore, reducing this length, even by a constant factor, is a critical issue. In this work we consider the following problem. Given a rooted XML tree T, label the nodes of T in the most compact way such that given the labels of two nodes, one can determine in constant time, by looking at the labels only, whether one node is an ancestor of the other. Labelings currently being used are all variants of the following interval scheme. Number the leaves say from left to right and label each node with a pair consisting of the numbers of its smallest and largest leaf descendants. An ancestor query then amounts to an interval containment test on the labels. The maximum label length using this scheme is 2 log n, where n is the number of nodes in the tree. (All logarithms in this paper are to base 2.) The focus of this work is finding a scheme that works best in practice on real XML data. We suggest an orthogonal prefix-based approach, where the labeling is such that an ancestor query roughly amounts to testing whether one label is a prefix of the other. We present several new labeling schemes based on this approach and analyze their performance both theoretically and empirically.     

Filling carbon nanotubes with particles

The filling of carbon nanotubes (CNTs) with fluorescent particles was studied experimentally and theoretically. The fluorescent signals emitted by the particles were visible through the walls of the nanotubes, and the particles inside the tubes were observable with an electron microscope. Taking advantage of the template-grown carbon nanotubes' transparency to fluorescent light, we measured the filling rate of the tubes with particles at room conditions. Liquids such as ethylene glycol, water, and ethylene glycol/water mixtures, laden with 50 nm diameter fluorescent particles, were brought into contact with 500 nm diameter CNTs. The liquid and the particles' transport were observed, respectively, with optical and fluorescence microscopy. The CNTs were filled controllably with particles by the complementary action of capillary forces and the evaporation of the liquid. The experimental results were compared and favorably agreed with theoretical predictions. This is the first report on fluorescence studies of particle transport in carbon nanotubes.     

10 Gbit/s optical wavelength converter with a Brillouin scattering-based spectral filter

For the first time, to our knowledge, a highly robust, high-bit-rate (10 Gbit/s) wavelength converter that is based on a narrow Brillouin filter is reported. The conversion takes place in a semiconductor optical amplifier (SOA) in a cross-gain-phase process. The SOA operates in a weak-modulation mode, and the exiting signal undergoes a dc reduction with a narrow spectral filter. In our system we perform spectrally narrow filtering by using a long Brillouin grating.     

On the effects of viscous dissipation and pressure work in free convection loops

The effects of viscous dissipation and pressure work are examined theoretically for laminar free convection loops. The appropriate governing equations are derived. Whereas previous work has considered only dissipation effects, the present paper shows that dissipation and pressure work effects are of comparable magnitude and must be considered together. Analytical solutions are presented for several open and closed loops. Both constant flux and constant temperature heating conditions are examined. Viscous dissipation and pressure work effects are found to have opposing influences on the flow in a loop. The former can enhance a flow for certain heating orientations, but the latter is usually dominant and retards a flow.     

Temporary Heating in Construction Contracts

It appears that in construction projects extending through winter with freezing temperatures, the cost of temporary heating is not always equitably resolved between the parties in a contract. Although existing guidelines have been initiated since 1964 by the construction industry, the bid allowances in calendar days and cost perdiem of heating, as suggested, have not been implemented. The three case studies described with varying structures and heating systems, show how heating costs are affected by changes beyond the General Contractor's control. These costs can be substantial; however, they can be minimized if owner, designer, contractor and mechanical subcontractor can cooperate.