Parallel correlated double sampling technique for pipelined analogue-to-digital converters

A new correlated double sampling technique that avoids the additional thermal noise penalty is presented. The new technique employs a low- gain two-stage opamp with the second stage made up of multiple gain stages in parallel. The superior noise performance of the proposed technique to correlated double sampling is shown.     

Acute View Auswirkungen der Biokraftstoffproduktion auf die Ernährungssicherheit

Ohne Zusammenfassung Eingegangen: 11. Februar 2009; angenommen: 12. Februar 2009     

满足多媒体处理器需求的动态电源管理技术

本文将介绍相关多媒体处理器的电源管理技术原理,以及如何利用这些技术降低功耗,并讨论采用哪些外部电源管理器件和功率IC可确保处理器芯片全面发挥省电特性.     

Correlated level shifting technique with cross-coupled gain-enhancement capacitors

A new technique is proposed to compensate for the loop gain degradation in correlated level shifting. The technique allows the use of a simple single-stage opamp with low gain to realise high effective loop gain. The effect of gain variations on the performance of the proposed correlated level shifting technique is discussed.     

Residual carbon dioxide as an index of feed efficiency in lactating dairy cows

High feed costs make feed conversion efficiency a desirable target for genetic improvement. Residual feed intake (RFI), calculated as the difference between observed and predicted intake, is a commonly used estimate of feed efficiency. However, determination of feed efficiency in dairy herds is challenging due to difficulties in measuring feed intake of individual animals reliably. Using residual CO₂ (RCO₂) production as an estimate of feed efficiency would allow ranking the cows according to feed efficiency, provided that CO₂ production is closely related to heat production and feed intake. The objective of this study was to evaluate the potential of RCO₂ as an index of feed efficiency using data from respiration calorimetry studies (289 cow per period observations). Heat production was precisely predicted from CO₂ production [root mean square error (RMSE)] adjusted for random effects was 1.5% of observed mean]. Dry matter intake (DMI) was better predicted from energy-corrected milk (ECM) yield and CO₂ production than from ECM yield and body weight in the model (adjusted RSME = 0.92 vs. 1.39 kg/d). Residual CO₂ production estimated as the difference between actual CO₂ production and that predicted from ECM yield, metabolic body weight was closely related to RFI (adjusted RMSE = 0.42) that was calculated as the difference between actual DMI and that predicted from ECM, metabolic body weight, and energy balance (EB). When the cows were categorized in 3 groups of equal sizes on the basis of RCO₂ (low, medium, and high), low RCO₂ cows had lower DMI, RFI, methane production and intensity (g/kg ECM), and heat production, but higher efficiency of metabolizable energy utilization for lactation than high RCO₂ cows. When RFI was predicted from RCO₂, the residuals (observed – predicted) were negatively related to EB and digestibility. Predicting RFI with a 2-variable model based on RCO₂ and digestibility, adjusted RMSE decreased to 0.23 kg/d, and residuals were not significantly related to EB. The cows in low RCO₂ group had a higher energy digestibility than the cows in the high RCO₂ group, and differences in EB were observed between the groups. Error of the model predicting residual ECM production from RCO₂ was 1.41 kg/d. The residuals were positively related to ECM yield and energy digestibility. Predicting residual ECM from RCO₂ and ECM yield decreased adjusted RMSE to 1.07 kg/d, and further to 0.78 kg/d when digestibility was included in the 2-variable model. It is concluded that RCO₂ has a potential for ranking individual cows based on feed efficiency.     

Public choice theory and rental housing: an examination of rental housing contracts in Ghana

This paper extends both the literature on rental housing in Ghana and the global literature on the critique of public choice analyses in terms of focus, methods and positioning. It argues that, contrary to the assumption that all housing policy changes are driven by internal national processes, in the case of Ghana at least, neither tenants (through their use of their greater numbers) nor landlords (through the use of their stronger financial and hence political power) exclusively influence housing policy. Both parties have some power, but landlords use theirs to change rents arbitrarily and decide whom to invite or keep as tenants, whilst tenants seek to use their power by lodging complaints with the state, albeit to little effect as the power of landlords is overwhelming. There is a strong basis to call into question the public choice argument that it is fair for landlords to extract windfall rent from tenants since their efforts or talents do not increase rent.     

Adjusted probabilistic route discovery in mobile ad hoc networks

Conventional on-demand route discovery methods in mobile ad hoc networks (MANET) employ simple flooding method, where a mobile node blindly rebroadcasts received route request (RREQ) packets until a route to a particular destination is established. This can potentially lead to high channel contention, causing redundant retransmissions and thus excessive packet collisions in the network. This paper proposed two new probabilistic methods that can significantly reduce the number of RREQ packets transmitted during route discovery operation. Our simulation analysis reveals that equipping AODV with an appropriate probabilistic route discovery method can result in significant performance improvements in terms of routing overhead, MAC collisions and end-to-end delay while still achieving a good throughput when compared with the traditional AODV.     

Face detection based on multilayer feed-forward neural network and Haar features

Fast and accurate detection of a facial data is crucial for both face and facial expression recognition systems. These systems include internet protocol video surveillance systems, crime scene photographs systems, and criminals' databases. The aim for this study is both improvement of accuracy and speed. The salient facial features are extracted through Haar techniques. The sizes of the images are reduced by Bessel down-sampling algorithm. This method preserved the details and perceptual quality of the original image. Then, image normalization was done by anisotropic smoothing. Multilayer feed-forward neural network with a back-propagation algorithm was used as classifier. A detection accuracy of 98.5% with acceptable false positives was registered with test sets from FDDB, CMU-MIT, and Champions databases. The speed of execution was also promising. An evaluation of the proposed method with other popular detectors on the FDDB set shows great improvement.     

Lanthanide doping of Li7La3-xMxZr2O12 (M=Sm,Dy, Er,Yb; x=0.1–1.0) and dopant size effect on the electrochemical properties

Lithium-ion batteries, as one of the energy storage devices, has attracted much attention due to its remarkable characteristics. However, they pose safety challenges because of their liquid electrolytes. Solid electrolytes are one of the key candidates to tackle the safety issues in Li-ion batteries. As a solid electrolyte, garnet-type Li₇La₃Zr₂O₁₂ is a promising candidate with its high stability against lithium metal and wide electrochemical window among its counterparts. But, the ionic conductivity is yet to be compared with liquid electrolytes. Hence, doping is still the common strategy to adjust the ionic conductivities. Despite the fact that doping with various elements is well-documented, Lanthanide group element doping is not thoroughly investigated. This research is to study the synthesis of garnet-type Li₇La_3-xM_xZr₂O₁₂ (M = Sm, Dy, Er, Yb; x = 0.0–1.0) novel compositions to enlighten the effect of lanthanide group element doping as a function of ionic radius. Results showed that increasing dopant ionic radius improves densification, diminishes Li-ion conduction and, except Yb case, expands the lattice. However, impurity phases formed when the solubility limit is reached, has overall a positive impact on Li-ion conduction. The highest ionic conductivity (0.15 mS/cm) and lowest activation energy (0.18 eV) without impurity phases were obtained from Yb doped LLZO. It was also found that the presence of LiDyO₂ improves the ionic conductivity to 0.16 mS/cm.