A Spatial‐Context‐Based Approach for Automated Spatial Change Analysis of Piece‐Wise Linear Building Elements

Changes of designs and construction plans often cause propagative design modifications, tedious construction coordination, cascading effects of errors, reworks, and delays in project management. Among various building elements, those having piece‐wise linear geometries (i.e., connected straight line segments), such as connected straight sections of ducts in mechanical, electrical, and plumbing systems, frequently undergo spatial changes in response to the changes of their surroundings. On the other hand, the piece‐wise linear geometries pose challenges to analyzing and controlling changes in construction and facility management. State‐of‐the‐art 3D change detection algorithms often face ambiguities about which points belong to which objects when piece‐wise linear object are spacked in small spaces. This article examines a spatial‐context‐based framework that uses spatial relationships between piece‐wise linear building elements (ducts in this article) to enable fast and reliable association of 3D data with ducts in as‐designed models for supporting reliable change analysis. Three case studies showed that this framework outperformed a conventional change detection method, and could handle large dislocations of piece‐wise linear elements and occlusions.     

Long‐term impact of nitrogen and potassium fertilizers on yield,soil nutrients and biochemical parameters of tea

A field experiment was conducted with tea cultivar UPASI‐9 over a period of 9 years to evaluate the long‐term effects of nitrogen (N) and potassium (K) fertilizers on yield, biochemical parameters, soil and leaf nutrient status. The yield increase was as high as 66% over the control for N application of 450 kg ha^?1 year^?1. Polyphenol and amino acid contents increased with increase in K application rate. Positive and significant correlation was found between nitrate reductase activity and the amino acid content of the tea shoots. While ammoniacal nitrogen in the soil was not affected by the application of fertilizer, ammonium acetate extractable K increased. The failure to apply fertilizer resulted in depletion of the organic matter status of the soil. Although increased rate of nitrogen application increased the overall yield of made tea (kg ha^?1 year^?1), the specific yield (kg kg^?1 N) declined. The soil tended to become acidic from frequent application of high doses of nitrogenous fertilizer. The leaf NK status was significantly influenced by the various treatments. Copyright © 2004 Society of Chemical Industry     

The computer analysis of space frames with offset members

The problems involved in the analysis of three dimensional frames having offset prismatic members are investigated. The sources of offset considered are the rigid gusset plate effects and misalignment of members from specified joint positions. The secondary effects due to axial forces are also considered in the analysis. The displacement method of structural analysis is used with an iterative procedure to take into account the secondary effects. The complete stiffness matrix has been derived. The computer program developed, based on this analysis, is also explained. From the example of steel frame folded plate it is seen that the difference in maximum axial forces and bending moments due to the offset members are about 20%. It appears that the method, developed herein, for analysing space frames having offset members, offers a very direct and versatile approach to the problem of analysing structures having misaligned members.     

CONTROL OF DEAD-TIME SYSTEMS USING HYBRID ANT COLONY OPTIMIZATION

This paper introduces two improved forms of the ant colony optimization (ACO) algorithm applied to a proportional integral derivative (PID) controller and Smith predictor design. Derivative free optimization methods, namely simplex derivative based pattern search (SDPS) and implicit filtering (IMF), are used to intensify the search mechanism in the ACO algorithm with improved convergence over the original ACO. The effectiveness of the controller schemes using the proposed algorithms, namely SDPS-ACO, and IMF-ACO, is demonstrated using unit step set point response for a class of dead-time systems, and the results are compared with some existing methods of controller tuning.     

Matched asymptotic solution for flow in a semi-hyperbolic die

A semi-hyperbolic converging geometry finds application as an inexpensive elongation rheometer under certain flow conditions. We provide a matched asymptotic solution for the flow of a Newtonian fluid under no-slip boundary conditions. The predicted velocity and pressure profiles agree nearly quantitatively with CFD simulated values. Our theoretical approach has certain advantages over the known similarity solution proposed by James (1991. A.I.Ch.E. Journal 37, 59-64).     

MATLAB modelling and examination of the effect of heat capacity of basin and glass cover on performance of solar still by thermal models

There are numerous researcher-developed mathematical models for single slope passive solar stills which considered the effect of heat capacities of basin and glass cover as negligible. The negligence parameter also plays a vital role in the prediction of the thermal performance of the system. In this paper, an effort has been made to evaluate the cumulative yield, energy efficiency and exergy efficiency of a single slope passive solar still with and without considering the heat capacities of basin and glass cover by using various thermal models such as Dunkle’s model, Zheng Hongfei et al.’s model and Tsilingiris model. These models were studied and compared with and without considering the heat capacity of solar components such as basin and glass cover. The thermodynamic model of this system is developed, and executed in a MATLAB code. By comparing the theoretical values of the cumulative yield, energy efficiency and exergy efficiency, it was found that consideration of the heat capacities of glass cover and basin gives a higher output in all the thermal models.     

The vocabulary and grammar of color patterns

We determine the basic categories and the hierarchy of rules used by humans in judging similarity and matching of color patterns. The categories are: (1) overall color; (2) directionality and orientation; (3) regularity and placement; (4) color purity; (5) complexity and heaviness. These categories form the pattern vocabulary which is governed by the grammar rules. Both the vocabulary and the grammar were obtained as a result of a subjective experiment. Experimental data were interpreted using multidimensional scaling techniques yielding the vocabulary and the hierarchical clustering analysis, yielding the grammar rules. Finally, we give a short overview of the existing techniques that can be used to extract and measure the elements of the vocabulary.     

Damage and its growth in laminated composite circular/rectangular plates undergoing large deformations

A nonlinear finite element static analysis is used to predict the damage in rectangular/circular plates due to large deformation simulating low-velocity impact. The impact due to the ball impactor is modelled by an equivalent static load and load distribution is taken according to Hertzian law. Tsai-Wu criterion is used to predict the failure of each ply at Gauss points. The failure mode (fibre breakage or matrix cracking) is identified using maximum stress criterion. The material properties at each failed Gauss point is degraded appropriately and the stress analysis is carried out again. This iterative process is repeated until no further damage condition occurs. Numerical examples for both circular and rectangular composite plates are presented.     

Effects of alternating and direct current in electrocoagulation process on the removal of cadmium from water

In practice, direct current (DC) is used in an electrocoagulation processes. In this case, an impermeable oxide layer may form on the cathode as well as corrosion formation on the anode due to oxidation. This prevents the effective current transfer between the anode and cathode, so the efficiency of electrocoagulation processes declines. These disadvantages of DC have been diminished by adopting alternating current (AC) in electrocoagulation processes. The main objective of this study is to investigate the effects of AC and DC on the removal of cadmium from water using aluminum alloy as anode and cathode. The results showed that the removal efficiency of 97.5 and 96.2% with the energy consumption of 0.454 and 1.002 kWh kl⁻¹ was achieved at a current density of 0.2 A/dm² and pH of 7.0 using aluminum alloy as electrodes using AC and DC, respectively. For both AC and DC, the adsorption of cadmium was preferably fitting Langmuir adsorption isotherm, the adsorption process follows second order kinetics and the temperature studies showed that adsorption was exothermic and spontaneous in nature.