An Integrated Voice Data Protocol for Slotted CDMA Personal Communication Networks

In this paper we propose a new protocol forintegrated voice/data traffic in personal communicationnetworks (PCNs) employing slotted packet code divisionmultiple access (CDMA). The concept of dynamic boundary is adopted in both code and timedomains to meet the different requirements for data andvoice traffic. This paper outlines and compares theperformance of three channel assignment policies. The network performance is measured in terms of theaverage voice blocking probability and average datadelay. A discrete-event simulation and a two-dimensionalMarkov model are developed for both the fixed boundary scheme and dynamic boundary scheme.The results indicate that an improved performance can beachieved by introducing the dynamic boundary scheme, andthe dynamic assignment policy results in a performance close to the optimal value. It isalso easier to be implemented.     

Progress towards marketable earth-abundant chalcogenide solar cells

Kesterite-related photovoltaic materials are considered a promising alternative to CdTe and Cu(In,Ga)(S,Se)₂ absorbers, primarily because they are not reliant on scarce elements such as indium and tellurium or the heavy metal cadmium. Recently, we reported a performance breakthrough for this materials class, reaching by a simple hydrazine-based deposition technique 9.6% power conversion efficiency for Cu₂ZnSn(S,Se)₄ devices (40% improvement over vacuum-based methods). Here, more detailed characterization for a hydrazine-prepared device shows the potential of this technology for further efficiency improvement. We also present initial device results for Cu₂ZnSn(S,Se)₄ films deposited using a mixed water-hydrazine-based solvent, yielding devices with 8.1% efficiency.     

Solution‐processed Cu(In,Ga)(S,Se)2 absorber yielding a 15.2% efficient solar cell

The remarkable potential for inexpensive upscale of solution processing technologies is expected to enable chalcogenide‐based photovoltaic systems to become more widely adopted to meet worldwide energy needs. Here, we report a thin‐film solar cell with solution‐processed Cu(In,Ga)(S,Se)₂ (CIGS) absorber. The power conversion efficiency of 15.2% is the highest published value for a pure solution deposition technique for any photovoltaic absorber material and is on par with the best nonvacuum‐processed CIGS devices. We compare the performance of our cell with a world champion vacuum‐deposited CIGS cell and perform detailed characterization, such as biased quantum efficiency, temperature‐dependent electrical measurement, time‐resolved photoluminescence, and capacitance spectroscopy. Copyright © 2012 John Wiley & Sons, Ltd.     

Transactions Papers - A Blind Adaptive MMSE Multiuser Detector over Multipath CDMA Channels and its Analysis

Based on the refinement-only fast subspace tracking (RO-FST) algorithm to adaptively estimate the signal sub-space, a blind adaptive SVD-based minimum-mean-square-error (MMSE) multiuser detector is proposed in this paper for asynchronous direct-sequence code-division-multiple-access (DS-CDMA) systems over multipath fading channels. Numerical results show that the proposed detector gives low computational complexity and good performance in terms of signal-to-interference-plus-noise ratio (SINR) and bit-error-rate (BER). In addition, we apply the perturbation analysis of the proposed adaptive detector to derive the closed-form expressions for the mean-square error (MSE) and SINR. The analytical results are shown to match well with the simulation results.     

Resettlement Issues of Cirata Dam Project: A Post-project Review

Forced population displacement caused by dam construction has been regarded as the most serious issue of water resources development. Nevertheless, the best practice is still not yet established. This paper aims to examine the performance of the involuntary resettlement scheme applied to the Cirata Dam project in Indonesia to obtain clues for improvement. Aquaculture development in the reservoir succeeded in creating new jobs for resettlers. Most resettlers ended up with less farmland than they had previously owing to the increase in land price. The land-for-land compensation scheme is preferable to cash compensation. Participation of resettlers in the planning and implementation of the resettlement scheme still had room for improvement. Some intermediate mechanism, between villagers and those implementing the resettlement scheme, should be devised. More careful and streamlined efforts should have been made as regards the secondary development of the project, so that those displaced could enjoy the benefits.     

Influence of initial CaCl2 concentration on the phase and morphology of CaCO3 prepared by carbonation

Calcium carbonate particles were prepared by bubbling the mixed gas CO₂/N₂ into CaCl₂ solution. The effect of initial CaCl₂ concentration on the morphology and phase of CaCO₃ was discussed with the help of XRD and SEM measurements. The samples prepared at low CaCl₂ concentration composed mainly of spherical vaterite. With the increase of CaCl₂ concentration, more and more rhombic particles were formed and mixed with spherical particles. When the initial CaCl₂ concentration increased to 0.3 mol/L, only rhombic calcite was formed in the final product. The change of CaCO₃ morphology with the increase of CaCl₂ concentration was attributed to the excess of Ca²⁺, which speeded the transformation of vaterite to calcite, thus more rhombic calcite was formed at higher CaCl₂ concentration.     

Thin-layer drying of cassava chips in multipurpose convective tray dryer: Energy and exergy analyses

Energy and exergy data of the drying of thin-layer cassava (Manihot esculenta) chips in a multipurpose convective-type tray dryer at 50 °C were collected to evaluate the technical performance of the drying system. The energy and exergy parameters, i.e. energy utilization, energy utilization ratio, energy efficiency, exergy inflow and outflow, exergy loss, and ex-ergetic efficiency were analyzed. The results indicate that the energy utilization, exergy inflow, exergy outflow, and exergy efficiency increased in the ranges of 9.53–24.66 kJ/s, 5.67–11.34 kJ/s, 2.21–8.04 kJ/s, and 38.90 %270.86 %, respectively, with increasing drying time. The results also show that the energy utilization ratio, energy efficiency, and exergetic improvement potential tend to decrease in the ranges of 0.49–0.68, 47.48 %–62.62 %, and 0.96–2.33 kJ/s, respectively, with increasing drying time. Additionally, stable exergy losses were observed during the drying process, within the range of 3.30–4.27 kJ/s during drying. Further research and development that could be used to improve the performance of this drying process are also suggested.

     

Comparison of CDMA and OFDM Systems for Broadband Power Line Communications

Direct sequence code division multiple access (DS-CDMA) and orthogonal frequency division multiplexing (OFDM) systems are two options for broadband power line communications. In this paper, a comparison is made between the CDMA and OFDM systems. The bit error rate (BER) performance and the optimum overall data rate of the CDMA and OFDM systems are analyzed and compared, using the criteria of the same bandwidth occupation, the same transmission power for each user, the same total number of users in the system and the same power line channel. The comparison is based on the analytical models that are developed and verified by simulations.     

Dairy products discrimination according to the milk type using an electrochemical multisensor device coupled with chemometric tools

This study shows the potential application of a potentiometric electronic tongue coupled with a lab-made DataLogger device for the classification of dairy products according to the type of milk used in their production, i.e., natural, fermented and UHT milk. The electronic tongue device merged a commercial pH electrode and 15 lipid/polymeric membranes, which were obtained by a drop-by-drop technique. The potentiometric signal profiles gathered from the 16 sensors, during the analysis of the 11 dairy products (with ten replicate samples), together with principal component analysis showed that dairy samples could be naturally grouped according to the three types of milk evaluated. To further investigate and verify this capability, a linear discriminant analysis together with a simulated annealing variable selection algorithm was also applied to the electrochemical data, which were randomly split into two datasets, one used for model training and internal-validation using a repeated K-fold cross-validation procedure (with 64% of the data); and the other for external validation purposes (containing the remaining 36% of the data). The multivariate supervised strategy used allowed establishing a classification model, based on the potentiometric information of four sensor lipid membranes, which enabled achieving a successful discrimination rate of 100% for both internal- and external-validation processes. The demonstrated versatility of the built electronic tongue for discriminating dairy products according to the type of milk used in their production combined with its simplicity, low-cost and fast time analysis may envisage a possible future application in dairy industry.     

Modeling of transfer Characteristics for the broadband power line communication channel

This paper presents a novel approach to model the transfer function of electrical power lines for broadband power line communication. In this approach, the power line is approximated as a transmission line and the two intrinsic parameters, the characteristic impedance and the propagation constants, are derived based on the lumped-element circuit model. Using these intrinsic parameters, the transfer characteristics for a N-branch power distribution network are derived based on the scattering matrix method. Detail derivation of this line model is given in this paper. The model has been verified with practical measurements conducted on actual power networks. It is demonstrated that the model accurately determine the line characteristics under different network configuration and when different household appliances are connected.