Open dumping site in Asian developing countries: a potential source of polychlorinated dibenz-p-dioxins and polychlorinated dibenzofurans

Open landfill dumping areas for municipal wastes in Asian developing countries have recently received particular attention with regard to environmental pollution problems. Because of the uncontrolled burning of solid wastes, elevated contamination by various toxic chemicals including dioxins and related compounds in these dumping sites has been anticipated. In this study, concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (PCBs) were determined in soils from dumping sites in the Philippines, Cambodia, India, and Vietnam. Residue concentrations of PCDD/Fs and coplanar PCBs in dumping site soils were apparently greater than those in soils collected in agricultural or urban areas far from dumping sites, suggesting that dumping sites are potential sources of PCDD/Fs and related compounds. Observed PCDD/F concentrations in soils from dumping sites in the Philippines and Cambodia were comparable or higher than those reported for dioxin-contaminated locations in the world (e.g., near the municipal waste incinerators and open landfill dumping sites). Homologue profiles of PCDD/Fs in dumping site soils from the Philippines and, to a lesser extent, from Cambodia and India reflected patterns of samples representing typical emissions, while profiles of agricultural or urban soils were similar to those of typical environmental sinks. This result suggests recent formation of PCDD/Fs in dumping site areas and that open dumping sites are a potential source of dioxins in Asian developing countries. Uncontrolled combustions of solid wastes by waste pickers, generation of methane gas, and low-temperature burning can be major factors for the formation of dioxins in dumping sites. Elevated fluxes of PCDD/Fs to soils in dumping sites were encountered in the Philippines, Cambodia, India, and Vietnam-Hanoi, and these levels were higher than those reported for other countries. Considerable loading rates of PCDD/Fs in the dumping sites of these countries were observed, ranging from 20 to 3900 mg/yr (0.12-35 mg TEQ/yr). PCDD/F concentrations in some soil samples from the Philippines, Cambodia, India, and Vietnam-Hanoi exceeded environmental guideline values, suggesting potential health effects on humans and wildlife living near these dumping sites. The estimated intakes of dioxins via soil ingestion and dermal exposure for children were higher than those for adults, suggesting greater risk of dioxin exposure for children in dumping sites. To our knowledge, this is the first comprehensive study on PCDD/Fs contamination in open dumping sites of Asian developing countries. On the basis of the result of this study, we have addressed a new environmental issue that open dumping sites are potential sources of PCDD/Fs and related compounds, and dioxin contamination in dumping sites may become a key environmental problem in developing countries.     

Prediction Models for Debonding Failure Loads of Carbon Fiber Reinforced Polymer Retrofitted Reinforced Concrete Beams

This study focuses on debonding failure in reinforced concrete beams with carbon fiber reinforced polymer composite bonded on the soffit using the wet lay-up method. An experimental study, which involved 26 tests, was carried out. The experiments showed two failure modes: Intermediate span debond and end debond. The first failure is the result of the high bond stress near the tip of a flexure-shear crack, whereas the second type of failure is due to the high shear stress developed in the weakest concrete layer at the tension reinforcement level. The experiments have shown that U-straps can be effective in preventing intermediate span and end debond. Based on experimental observations, two simple and practical theoretical models were developed and verified with the experimental data, together with a large database of other existing tests.     

Synthesis and properties of styrene–EPDM–vinyl acetate graft polymer

The styrene–EPDM–vinylacetate (SEV) graft polymer, which linked respectively the styrene (St) unit and vinylacetate the (VAc) unit to the ethylene–propylene–diene terpolymer (EPDM) backbone was synthesized by two‐step graft polymerizations: First the graft polymerization of VAc onto EPDM was carried out, and then St was added successively in the prepolymerized solution and further polymerized for a given period to obtain SEV. The effects of concentration of EPDM and an initiator, mole ratio of VAc to St, polymerization time, temperature, and solvent were examined on the graft polymerizations. The synthesized graft polymers (SEVs) that have different contents of St or VAc were identified by Fourier transform IR spectrum. The highest graft ratio has been obtained by 10 wt % of EPDM, 1.0 mole ratio of VAc to St, and 1.0 wt % of BPO in toluene for 48 h at 70°C. The glass transition temperature of SEV is lower than that of poly(vinyl acetate) (PVAc) and polystyrene (PS). The thermal stability of SEV is higher than that of PVAc, PS, and the acrylonitrile–butadiene–styrene (ABS) resin. The tensile strength of SEV was improved as compared with that of EPDM. The light resistance and weatherability of SEV were better than those of ABS. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2296–2304, 2000     

Determination of the heat transfer coefficient from short‐shots studies and precise simulation of microinjection molding

The filling process of a micro‐cavity was analyzed by modeling the compressible filling stage by using pressure‐dependent viscosity and adjusted heat transfer coefficients. Experimental filling studies were carried out at the same time on an accurately controlled microinjection molding machine. On the basis of the relationship between the injection pressure and the filling degree, essential factors for the quality of the simulation can be identified. It can be shown that the flow behavior of the melt in a micro‐cavity with a high aspect ratio is extremely dependent on the melt compressibility in the injection cylinder. This phenomenon needs to be considered in the simulation to predict an accurate flow rate. The heat transfer coefficient between the melt and the mold wall that was determined by the reverse engineering varies significantly even during the filling stage. With increasing injection speed and increasing cavity thickness, the heat transfer coefficient decreases. It is believed that the level of the cavity pressure is responsible for the resulting heat transfer between the polymer and the mold. A pressure‐dependent model for the heat transfer coefficient would be able to significantly improve the quality of the process simulation. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Using a Short Wavelength Infrared (SWIR) hyperspectral imaging system to predict alpha amylase activity in individual Canadian western wheat kernels

Sprout damage (pre-harvest germination) in wheat results in highly deleterious effects on end-product quality. Alpha-amylase, the pre-dominant enzyme in the early stage of sprouting has the most damaging effect. This paper introduces a new method using a SWIR hyperspectral imaging system (1000–2500 nm) to predict the α-amylase activity of individual wheat kernels. Two classes of Canadian wheat, Canada Western Red Spring (CWRS) and Canada Western Amber Durum (CWAD), with samples of differing degrees of sprout damage were investigated. Individual kernels were first imaged with the hyperspectral imaging system and then the α-amylase activity of each kernel was determined analytically. Individual kernel α-amylase activity prediction was significant (R ² 0.54 and 0.73) for CWAD and CWRS, respectively using Partial Least Square regression on the hyperspectral data. A classification method is proposed to separate CWRS kernels with high α-amylase activity level from those with low α-amylase activity giving an accuracy of above 80%. This work shows that hyper/multi-spectral imaging techniques can be used for rapidly predicting the α-amylase activity of individual kernels, detecting sprouting at early stage.     

Effect of ultrasound on removal of persistent organic pollutants (POPs) from different types of soils

A new and promising technology is utilization of sonochemistry on decontamination of polluted soil. The feasibility of this technology on treatment of contaminated soils (synthetic clay, natural farm clay, and kaolin) was studied by using two target persistent organic pollutants (POPs): hexachlorobenzene (HCB) and phenanthrene (PHE). The soils were highly contaminated in 500 mg/kg. The laboratory experiments were conducted with various conditions (moisture, power, and time duration). The effects of these parameters on ultrasonication (as well as the removal of contaminants) were examined. The reasonable moisture ratio of the slurry could be in range of 2:1–3:1. The process did not change pH values of soils. Experimental results showed that ultrasonication has a potential to reduce the high concentrations of these POPs.     

Downlink queuing model and packet scheduling for providing lossless handoff and QoS in AG mobile networks

Next generation mobile networks are expected to provide seamless personal mobile communication and quality-of-service (QoS) guaranteed IP-based multimedia services. Providing seamless communication in mobile networks means that the networks have to be able to provide not only fast but also lossless handoff. This paper presents a two-layer downlink queuing model and a scheduling mechanism for providing lossless handoff and QoS in mobile networks, which exploit IP as a transport technology for transferring datagrams between base stations and the high-speed downlink packet access (HSDPA) at the radio layer. In order to reduce handoff packet dropping rate at the radio layer and packet forwarding rate at the IP layer and provide high system performance, e.g., downlink throughput, scheduling algorithms are performed at both IP and radio layers, which exploit handoff priority scheduling principles and take into account buffer occupancy and channel conditions. Performance results obtained by computer simulation show that, by exploiting the downlink queuing model and scheduling algorithms, the system is able to provide low handoff packet dropping rate, low packet forwarding rate, and high downlink throughput.     

Dexterous manipulation of an object by means of multi‐DOF robotic fingers with soft tips

This article analyzes the dynamics of motion of various setups of two multiple degree‐of‐freedom (DOF) fingers that have soft tips, in fine manipulation of an object, and shows performances of their motions via computer simulation. A mathematical model of these dynamics is described as a system of nonlinear differential equations expressing motion of the overall fingers‐object system together with algebraic constraints due to tight area contacts between the finger‐tips and surfaces of the object. First, problems of (1) dynamic, stable grasping and (2) regulation of the object rotational angle by means of a setup of dual two‐DOF fingers, are treated. Second, the problem of regulating the position of the object mass center by means of a pair of two‐DOF and three‐DOF fingers is considered. Third, a set of dual three‐DOF fingers is treated, in order to let it perform a sophisticated task, which is specified by a periodic pattern of the object posture and a constant internal force. In any case, there exist sensory‐motor coordinations, which are described by analytic feedback connections from sensing to actions at finger joints. In the cases of setpoint control problems, convergences of motion to secure grasping together with the specified object rotational angle and/or the specified object mass center position, are proved theoretically. A constraint stabilization method (CSM) is used for solving numerically the differential algebraic equations to show performances of the proposed sensory‐feedback schemes. © 2002 Wiley Periodicals, Inc.