Avoiding Change Orders in Public School Construction

Increased student enrollment and the current poor state of the educational infrastructure require the construction of more school buildings and the renovation of many of the existing ones. The large number and magnitude of change orders in these projects constitute an impediment to the rapid and economic delivery of these projects. A total of 6,585 change orders filed in a school district’s projects in the 5 1/2 year period from 1999 to 2004 were analyzed in five categories including owner-directed changes, code compliance issues, errors/omissions in contract documents, discovered or changed conditions, and others. The results of the study indicate that the dollar value of change orders relative to the original contract can be reduced if preventive measures are taken. These measures include choosing the right construction management firm, emphasizing the definition of project scope early in the project, and effectively managing the precontract activities by conducting value engineering and constructability reviews. The results indicate that school projects can be completed with change orders not exceeding 5% of the contract value if these measures are taken. This study is of relevance to practitioners involved in school design and construction projects.     

Variable Bias Current in Magnetic Bearings for Energy Optimization

We introduce an adaptive variable bias current control scheme to minimize the energy consumption of magnetic bearings without altering the dynamic performance. We developed analytical expressions for the optimum bias current settings for both differential and unidirectional modes of operation as a function of the orbit size and the desired bearing stiffness. The orbit size is measured in situ by a recursive Fourier coefficient calculation. The analytical results are presented in normalized variables, and hence can be applied to any size and type of magnetic bearing. Both zero and nonzero static load cases are considered. We show analytically that, under variable bias current operation, the differential mode provides better energy efficiency and stiffness capacity than the unidirectional mode. We present the energy consumption data obtained experimentally on a flexible rotor magnetic bearing rig. The data show that, with the proposed variable bias current approach, a significant energy saving can be obtained without deterioration of dynamic performance     

Determination of optimum hazelnut roasting conditions

The objective of this study was to test the hypothesis that the roasting conditions used for hazelnuts, such as the air temperature, air velocity and roasting time (independent variables), could be optimized by using Response Surface Methodology. Effects of independent variables on sensory and physical characteristics were determined. A consumer test was used to determine the acceptable samples. Very dark and very light roasted samples, corresponding to 165 °C, 3 m/s, 25 min and 125 °C, 1 m/s, 15 min process conditions, respectively, were unacceptable. Superimposed contour plots were used to determine the values of independent variables and these showed the process conditions where all product characteristics were acceptable to consumers. At low velocity (0.3 m/s), acceptable products were produced at about 165–179 °C for 20–25 min. When air velocity increased, air temperature shifted to lower temperatures. Samples roasted at 145 °C, 2 m/s, 28 min, 165 °C, 1 m/s, 25 min and 145 °C, 3.7 m/s, 20 min produced the most acceptable products. The sample roasted at 165 °C, 1 m/s, 25 min required the least air velocity and was the most economical in terms of energy consumed among the samples rated most acceptable by consumers.     

Wet Forward Combustion for Heavy Oil Recovery

The purpose of this study was to perform wet forward combustion experiments for Bati Kozluca heavy oil under different experimental conditions. In the experiments, a vertical combustion tube was packed with crushed limestone and saturated with crude oil and water. A total of five wet combustion tube runs were conducted. It was observed that peak temperatures were higher when stabilized combustion was achieved and decreased as the combustion front approached the outlet of combustion tube. In wet combustion experiments, excess carbon dioxide productions were observed due to the decomposition of carbonate minerals. The concentration of carbon dioxide increased after the injection of water while the concentration of the oxygen and carbon monoxide decreased. Atomic H/C ratio of the fuel consumed decreased as the average peak temperature increased. Fuel consumption rate also decreased as the water-air ratio increased. The oil recovery was increased with the water injection until the optimum value. After this point, a decrease in oil recovery was observed due to the decrease in peak temperatures in Bati Kozluca crude oil. The main advantage of wet combustion was to reduce air requirements and improve the sweep efficiency by expanding the steam plateau region. Since most of the oil was displaced ahead of the burning front, the steam plateau becomes the primary driving mechanism for oil production.     

Bioactive components and antioxidant capacities of different miniature tomato cultivars grown by altered fertilizer applications

This study investigated the organic acid and phenolic compound levels, total phenolic (TP) and antioxidant capacity (TEAC) of three miniature tomato cultivars grown on a farmer’s field with three different fertilizer applications. Analysis of phenolic compound (protocatechuic, vanillic, gallic, chlorogenic, caffeic, syringic, p-coumaric and ferulic acid, rutin, quercetin, catechin and phloridzine) organic acid (citric, tartaric, malic, succinic and fumaric acid), TP and TEAC levels in fruit samples showed statistically significant (p?<?0.05) differences between tomato cultivars and fertilizer applications. Rutin and chlorogenic acid were the predominant phenolic compounds found in all three cultivars. The highest rutin value (50.48 mg kg^?1 FW) was found in the Black Zebra fertilized with DAP plus organic and biochemical fertilizers and the lowest (20.52 mg kg^?1 FW) in the Black Zebra fertilized with DAP only. The highest chlorogenic acid value (63.31 mg kg^?1 FW) was found in the sweet pea currant fertilized with DAP only and the lowest (21.06 mg kg^?1 FW) in the Black Zebra fertilized with DAP plus chemical fertilizer. Citric acid content was the dominant organic acid in all three cultivars, with the highest citric acid value (6439.50 mg kg^?1 FW) found in the Sweet Pea Currant cherry tomato fertilized with DAP plus organic and biochemical fertilizers and the lowest (2435.20 mg kg^?1 FW) in the Window Box Yellow fertilized with DAP plus chemical fertilizer. Total phenolic and antioxidant levels in the window box yellow were significantly lower as compared to the Black Zebra and sweet pea currant varieties for all three fertilizer applications.     

Removal of basic and acid dyes from aqueous solutions by a waste containing boron impurity

In this study, batch experiments were carried out for the sorption of basic blue 41 (BB 41), and acid blue 225 (AB 225) onto boron waste (BW) from boron enrichment plant. The operating variables studied are the initial dye concentration, contact time, solution pH, and adsorbent dosage. The experimental equilibrium data were analyzed by using various adsorption isotherm models and the results have shown that the adsorption behavior of AB 225 and BB 41 could be described well reasonably by Langmuir and Temkin isotherms, respectively. Kinetics studies indicated that the adsorption of both dyes follow pseudo-second-order kinetics. The sorption of basic dye increased at high pH values, whereas the opposite was true for acidic dye. The results indicate that BW could be employed as low-cost alternatives to the commercially available adsorbents in wastewater treatment for the removal of acid and basic dyes.     

Susceptor-assisted fast microwave sintering of TiN reinforced SiAlON composites in a single mode cavity

In the present study, 17 wt % TiN reinforced α-β SiAlON composites were sintered at low temperature by susceptor-assisted microwave heating. The effect of TiN addition on dielectrical properties of starting powders, as well as the influence of sintering temperature on phase evolution, microstructure development and mechanical properties of α/β-SiAlON-TiN composites were investigated. The obtained results showed that TiN addition increased the microwave absorbing properties which is reflected in the peak sintering temperature. Thus, the α:β ratio decreased and mechanical properties were improved, especially the fracture toughness of the composites. Furthermore, an estimate of energy consumption during microwave assisted sintering at the laboratory scale is presented. As a result, the highest values for relative density (97.1%), Vickers hardness (13.35 ± 0.47 GPa), and fracture toughness (7.52 ± 0.54 MPa m^1/2) were obtained by microwave sintering for 30 min at 1300 °C.     

A deep learning-based CEP rule extraction framework for IoT data

The Journal of Supercomputing - With the recent developments in Internet of Things (IoT), the number of sensors that generate raw data with high velocity, variety, and volume is tremendously...     

Effect of XRD relative intensities of the Li (002) on surface,optical and electrochemical impedance spectroscopy analyses of the deposited LiCoO<Subscript>2</Subscript> thin film

In this paper, the effect of RF power on LiCoO₂ thin films was investigated using X-ray diffractometer (XRD), atomic force microscopy, UV–Vis spectrophotometer, and potentiostat. The microstructural, surface, optical and electrochemical impedance measurements were performed to LiCoO₂ thin films, are used to for the fully solid-state battery cathode material. According to obtained results, the relative intensities of the Li (002) crystal phase in XRD patterns of deposited LiCoO₂ thin films were increased by increasing applied RF power, for the first time. The intensity of the LiCoO₂ (104) plane is nearly invariant. The relative intensities of the LiCoO₂ (113) plane were decreased by increasing RF power. The peak locations of the Li (002) and LiCoO₂ (104) were not changed. It was found that Li (002) relative intensities affect the all investigated parameters for the LiCoO₂ thin films. Especially, transmittance value increased about 20%. The band gap of the deposited film was changed 100–300 meV drastically. Deposited samples are shown high transparency in the visible region. Randles circuit was used for the equivalent circuit model. Nyquist plots, fitting parameters values and value of the circuit elements were estimated by ZSim software.     

TPS3: A privacy preserving data collection protocol for smart grids

Smart grid (SG) allows for two-way communication between the utility and its consumers and hence they are considered as an inevitable future of the traditional grid. Since consumers are the key component of SGs, providing security and privacy to their personal data is a critical problem. In this paper, a security protocol, namely TPS3, is based on Temporal Perturbation and Shamir’s Secret Sharing (SSS) schemes that are proposed to ensure the privacy of SG consumer’s data. Temporal perturbation is employed to provide temporal privacy, while the SSS scheme is used to ensure data confidentiality. Temporal perturbation adds random delays to the data collected by smart meters, whereas the SSS scheme fragments these data before transmitting them to the data collection server. Joint employment of both schemes makes it hard for attackers to obtain consumer data collected in the SG. The proposed protocol TPS3 is evaluated in terms of privacy, reliability, and communication cost using two different SG topologies. The performance evaluation results clearly show that the TPS3 protocol ensures the privacy and reliability of consumer data in SGs. The results also show that the tradeoff between the communication cost and security of TPS3 is negligible.