Experimental investigation of thermal performance of solar air heater having different obstacles on absorber plates

This paper presents the results of an experimental investigation of the performance for a new flat plate solar air heater (SAH) with several obstacles (Type I, Type II, and Type III) and without obstacles (Type IV). The efficiencies, the heat gain factors and heat loss coefficients are determined for the collectors and comparisons were made among them. The experimental data along with the correlations obtained by linear regression are presented. The optimal value of efficiency was determined for the solar air heater with Type II absorbent plate in flow channel duct for all operating conditions and the collector supplied with obstacles appears significantly better than that without obstacles.     

Chemical composition and physicochemical properties of tubera salep produced from some Orchidaceae species

Salep samples obtained from 10 different Orchidaceae spp., namely Dactylorhiza osmanica var. osmanica, Ophrys mammosa, Orchis anatolica, Orchis coriophora, Orchis italica, Orchis morio, Orchis palustris, Orchis simia, Orchis tridentata and Serapias vomeracea ssp. orientalis, in Anatolia, were analyzed for moisture, glucomannan, starch, protein, ash contents, pH and viscosity values. Depending on the species, the samples showed statistically significant differences in glucomannan, starch and viscosity values. It was observed that the salep samples obtained from the tubers of O. italica, O. morio, O. anatolica and O. tridentata and S. vomeracea ssp. orientalis, respectively, had higher glucomannan contents and viscosities. To ensure a supply of high-quality salep, the uncontrolled collection of tubers from the wild, especially the species O. italica, O. morio and O. anatolica, should be prevented, and research into methods of cultivation should be carried out.     

Modelling of the drying of eggplants in thin-layers

In this paper, the thin‐layer drying behaviour of eggplant slices (6 mm thick layers) in a convective‐type cyclone dryer is reported. Thin‐layer drying experiments were conducted at drying air temperatures of 55, 65 and 75 °C and dry air velocities of 1 and 1.5 ms^?1. Data on sample mass, temperature and velocity of the dry air were recorded continuously during each test. In order to estimate and select a suitable form of the drying curve, eight different semi‐theoretical and/or empirical models were fitted to the experimental data and comparisons made of their coefficients of determination as predicted by non‐linear regression analysis. The Page model best described the drying curve of eggplant, with a correlation coefficient, r = 0.9999.     

Bipedal robot walking control on inclined planes by fuzzy reference trajectory modification

The two-legged humanoid structure has advantages for an assistive robot in the human living and working environment. However, the control of bipedal walk is a challenge. Walking performance on solely even floor is not satisfactory. This paper presents a study on bipedal walk on inclined planes with changing slopes. A Zero Moment Point (ZMP) based gait synthesis technique is employed. The pitch angle reference for the foot sole plane—as expressed in a coordinate frame attached at the robot body—is adjusted online by a fuzzy logic system to adapt to different walking surface slopes. Ankle pitch torques and the average value of the body pitch angle, computed over a history of a predetermined number of sampling instants, are used as the inputs to this system. The proposed control method is tested via walking experiments with the 29 degrees-of-freedom human-sized full-body humanoid robot SURALP (Sabanci University Robotics Research Laboratory Platform) on even floor and inclined planes with different slopes. The results indicate that the approach presented is successful in enabling the robot to stably enter, ascend and leave inclined planes with 15?% (8.5°) grade. This, to the best knowledge of the authors, constitutes the steepest ascend reported to date, with a transition from even floor, by a blind walking biped robot.     

Smart Antenna Based OVSF Code Assignment for WCDMA Networks

This paper presents a new method for dynamic allocation of orthogonal variable spreading factor (OVSF) codes in WCDMA networks where each base station is equipped with an adaptive antenna array (AAA). Previous works about OVSF code assignment problem deal with the code limited case. Here, we investigate the feasibility to turn the problem into the SIR limited case. With our scheme, the new call request is allocated an OVSF code that may be currently used by an active user whose downlink beam has the smallest spatial correlation with the channel vector of the requesting user, as long as desired SIR level is achieved. The performance of the new scheme is justified through computer simulations under different traffic load conditions.     

Causes of Collapse and Damage to Low-Rise RC Buildings in Recent Turkish Earthquakes

This study assesses performance objectives defined in the Turkish Earthquake Code (TEC) in order to make a realistic evaluation related to heavy damage and collapse reasons of reinforced concrete (RC) buildings that experienced severe earthquakes in Turkey. A series of three-dimensional RC buildings with different characteristics and representing low-rise structures damaged and collapsed in the earthquake areas is designed according to Turkish codes (Turkish Design Standards and Turkish Earthquake Code). Pushover analyses are carried out to determine nonlinear behavior of the buildings under earthquake loads. Building performances are determined by using the displacement coefficients method, which is a commonly used nonlinear static evaluation procedure for different seismic hazard levels defined in the TEC. The stipulated performance objectives in the TEC are checked in terms of plastic rotations and maximum story drift. From the results of this research, it can be concluded that low-rise RC buildings designed according to Turkish codes sufficiently provide for the performance objectives stipulated in the TEC. Reasons for the heavy damages and collapses of RC buildings during severe earthquakes are explained by commonly occurring themes (i.e., project errors, poor quality of construction, modifications of buildings, etc.).     

An Investigation on the Aggregate Behavior of Firm Relocations to New Jersey (1990–1999) and the Underlying Market Elasticities

This paper reports the key results of an in depth analysis of ten years worth of data about business relocations to the State of New Jersey. The analyses have focused on the key geographic patterns of business relocations, and an econometric investigation of the role of transportation accessibility on the business relocation process. The estimated models focus on explaining the business relocation behavior, as well as the business relocation flows from the original locations to New Jersey.The first model assumes that the probability of a business relocating to a given location in New Jersey is a function of the combined attraction to the economic poles of New York City and Philadelphia. The results obtained suggest the existence of two opposing trends concerning the role played by New York City. The discrete choice models estimated provide additional insights into the role of transportation accessibility, suggesting that the type of economic activity performed by the firm shapes the firm’s valuation of accessibility to markets.The paper also studied the role of transportation accessibility as an explanatory variable of the business relocation flows by means of estimating aggregate demand models and destination constrained gravity models. In all cases the authors were able to estimate statistically significant and conceptually valid models that explain the aggregate behavior of the variables under study. These models were estimated for both the total number of relocations (all firms) as well as the major industry types. The resulting models were used to compute the elasticities with respect to accessibility variables. The chief conclusion is that different industry types exhibit different elasticities.In order to do the computations for the elasticities of the gravity model, the authors developed a mathematical formulation. Simply stated, this formulation demonstrates that the elasticity of the spatial interaction between an origin i and a destination j is simply the summation of the elasticities at the production end, and at the destination. The market elasticity is then computed as the weighted average of the elasticities for each of the market segments.     

Optimization of synthesis parameters for catalytic performance of Ni–B catalysts using response surface methodology

Hydrogen production through hydrolysis of sodium borohydride (NaBH₄) by using metal catalysts is promising for fuel cell applications. Nickel (Ni) and its alloys are favorable due to their high catalytic activity, relatively low cost and availability. In present study, the effects of temperature, pH, reduction rate and reducing agent concentration, which significantly affect the catalyst performance, were investigated using the response surface methodology (RSM). A mathematical model was derived according to results which were obtained from four-level orthogonal Taguchi L16 (4⁴) experimental design used for the optimization of multiple parameters in the process. From the RSM analyses, that compatible with the predicted experimental results, maximum hydrogen generation rate (HGR) 49.81 L min^?1 g_cat^?1 was obtained temperature of 278.12 K, pH of 5.52, reducing agent concentration of 85.96 NaBH₄.water^?1 and reduction rate of 6.82 mL min^?1. Analysis of variance reveals that both pH and rate of reduction have significant effect than the temperature on the HGR.