Operating swarm robots has the virtues of improved performance, fault tolerance, distributed sensing, and so on. The problem is, high overall system costs are the main barrier in managing a system of foraging swarm robots. Moreover, its control algorithm should be scalable and reliable as the foraging (search) spaces become wider. This paper analyzes a nature-inspired cooperative method to reduce the operating costs of the foraging swarm robots through simulation experiments. The aim of this research is to improve efficiency of mechanisms for reducing the cost by developing a new algorithm for the synergistic cooperation of the group. In this paper, we set the evaluation index of energy efficiency considering that the mission success rate as well as energy saving is important. The value is calculated as the number of successful operations against the total consumption of energy in order to also guarantee optimized for the work processing power than the one simple goal of energy savings. The method employs a behavioral model of a honey bee swarm to improve the energy efficiency in collecting crops or minerals. Experiments demonstrate the effectiveness of the approach. The experiment is set a number of strategies to combine the techniques to the proposed and conventional methods. Considering variables such as the area of search space and the size of a swarm, the efficiency comparison test is performed. As the result, the proposed method showed the enhanced energy efficiency of the average 76.9% as compared to the conventional simple model that means reduction of the recharging cost more than 40%.

Delta-sigma modulators (DSMs) are commonly use in high-resolution analog-to-digital converters, and band-pass delta-sigma modulators have recently been used to convert IF signals into digital signals. In particular, a quadrature band-pass delta-sigma modulator can achieve a lower total order, higher signal-to-noise ratio (SNR), and higher bandwidth when compared with conventional band-pass modulators. The current paper proposes a second-order three-bit quadrature band-pass delta-sigma modulator that can achieve a lower power consumption and better performance with a similar die size to a conventional fourth-order quadrature band-pass delta-sigma modulator (QBPDSM). The proposed system is integrated using CMOS 0.35 µm, double-poly, four-metal technology. The system operates at 13 MHz and can digitize a 200 kHz bandwidth signal centered at 4.875 MHz with an SNR of 85 dB. The power consumption is 35 mW at 3.3 V and 38 mW at 5 V, and the die size is 21.9 mm2.

A method to reduce the bandwidth between texture memory and the rasterization processor is proposed. It achieves the reduction by not fetching useless texels from texture memory in bilinear filtering. Since it does not depend on cache and loss compression, it can be used in applications where the reusability of texels is low and loss compression is prevented.

This paper proposes two high-performance multi-threshold-voltage CMOS (MTCMOS) F/Fs that are based on the CMOS hybrid-latch F/F and the CMOS semi-dynamic F/F. The proposed F/Fs utilize a clock-gating technique or a data recovery circuit in order to preserve their logic states in the power-down mode. They can change operation modes whether the clock level is high or low, and they provide outputs to fanouts in the power-down mode. When compared with existing clock-free MTCMOS F/Fs, the proposed MTCMOS hybrid-latch F/F shows maximum reduction of average delay, average power, and average power-delay product by 33%, 46%, and 63% for the supply voltage ranging from 0.8 V to 1.2 V. Although outperformed by the MTCMOS hybrid-latch F/F, the proposed MTCMOS semi-dynamic F/F inherits the benefit of the embedded logic from the CMOS SD F/F. Experimental results indicate that the MTCMOS semi-dynamic F/F can be used to implement a logic circuit that is superior to the one designed using the MTCMOS hybrid-latch F/F in speed, power, and area.

This paper presents a low profile high-efficiency transmitarray (TA) antenna based on a hybrid frequency selective surface (FSS). The hybrid FSS consists of two types of unit cells that have different incident angles and TE/TM polarization. This design minimizes the performance degradation caused by the oblique incident angle when designing a low profile TA antenna. In addition, the set of transmission phases to minimize transmission loss is selected by employing the optimal output phase reference. To verify its feasibility, a low profile TA (focal length/diameter of FSS =0.24) antenna that employs a unit patch antenna with a low gain and wide beamwidth as a feed antenna without an additional structure is designed. The simulated and measured results are in good agreement. In particular, the high simulated and measured aperture efficiencies of 42.7% and 41.9%, respectively, are obtained at 10GHz, respectively.

This paper proposed a region-based curve control function to detect the brain ventricle area by utilizing a geodesic active contour model. This is based on the average brightness of the brain ventricle area which is brighter in MRI images. Compared numerically by using various types of measurements, the proposed method can detect the brain ventricle area better than the existing methods.

This letter presents two high-performance level-converting flip-flops (LCFF) for multi-VDD systems, indirect precharging flip-flop (IPFF) and multi-supply complementary pass-transistor flip-flop (MCPFF). Employing a simple precharging scheme, IPFF provides high operating speed. MCPFF, on the other hand, provides low power operations by implementing the edge-triggering function with complementary pass transistors. Performance comparison indicates that IPFF operates at the highest speed and MCPFF consumes the lowest power among the seven LCFFs under evaluation.

Integral image is the sum of input image pixel values. It is mainly used to speed up the process of a box filter operation, such as Haar-like features. However, large memory capacity for integral image data can be an obstacle in an embedded environment with limited hardware. In a previous research, [5] reduced the size of integral image memory using 2×2 block structure with additional calculations. It can be easily extended to n×n block structure for further reduction, but it requires more additional calculations. In this paper, we propose a new block structure for the integral image by modifying the location of the reference pixel in the block. It results in much less additional calculations by reducing the number of memory accesses, while keeping the same amount of memory as the original block structure.

A modified illumination technique recently developed is known to improve the resolution and DOF (depth of focus) dramatically. But, it requires substantial modification in optical projection system and has some problems such as low throughput caused by low intensity and poor uniformity. And it is very difficult to adjust illumination source according to pattern changes. To solve these problems, we developed a new illumination technique, named ATOM (Advanced Tilted illumination On Mask) which applies the same concept as quadrupole illumination technique but gives many advantages over conventional techniques. This newly inserted mask gives drastic improvements in many areas such as DOF, resolution, low illumination intensity loss, and uniformity. In our experiments, we obtained best resolution of 0.28µm and 2.0µm DOF for 0.36µm feature sizes with i-line stepper, which is two times as wide as that of conventional illumination technique. We also obtained 0.22µm resolution and 2.0µm DOF for 0.28µm with 0.45NA KrF excimer laser stepper. For complex device patterns, more than 1.5 times wider DOF could be obtained compared to conventional illumination technique. From these results, we can conclude that 2nd generation of 64M DRAM with 0.3µm design rule can be printed with this technology combined with high NA (0.5) i-line steppers. With KrF excimer laser stepper, 256M DRAM can be printed with wide DOF.

A 116 arrayed waveguide grating multiplexer operating around 1550 nm has been realized using newly synthesized fluorinated poly(arylene ethers). The channel spacing is 0.8 nm (100 GHz). The insertion loss of the multiplexer is 17-20 dB and the cross talk is less than -15 dB. The propagation loss of a rib waveguide is less than 0.5 dB/cm at 1550 nm.

In this paper, an improved B-picture coding algorithm based on the symmetric bi-directional motion estimation (ME) is proposed. In addition to the block match error between blocks in the forward and backward reference frames, the proposed method exploits the previously-reconstructed template regions in the current and reference frames for bi-directional ME. The side match error between the predicted target block and its template is also employed in order to alleviate block discontinuities. To efficiently perform ME, an initial motion vector (MV) is adaptively derived by exploiting temporal correlations. Experimental results show that the number of generated bits is reduced by up to 9.31% when the proposed algorithm is employed as a new macroblock (MB) coding mode for the H.264/AVC standard.

An LDPC-coded FH-OFDMA system is proposed for the uplink of a packet-based cellular system, where the frequency hopping (FH) is based on a resource block (RB) for coherent demodulation. For the system, different RB types are employed either for better intercell interference (ICI) averaging capability or for better channel estimation performance. For the receiver, practical iterative channel estimation and decoding methods are proposed to improve the channel estimation performance without boosting the pilot power and to mitigate the adverse effects of the ICI. Extensive simulation results are provided to show the effect of the RB size on the channel estimation and ICI averaging performance as well as possible application of the proposed receiver in harsh mobile environments with dynamic packet allocation.

This paper deals with the small-scale fading distribution for UWB channels in the absence and presence of human bodies in indoor line-of-sight (LOS) environments and performance analysis of UWB systems considering the small-scale fading distribution. To obtain small-scale fading statistics, the channel measurements are performed in five representative environments that have different structure and size while locating the receiver (Rx) antenna on 49 (7×7 grid) local points with a fixed transmitter (Tx) antenna in each environment. The measured channel data are processed by a vector network analyzer and the target frequency bands range from 3 to 4.6GHz. From the measured data, we find the best fitted channel model among several typical theoretical distribution models such as Lognormal, Nakagami, and Weibull distributions, showing good agreement with the empirical channel data. We analyze the amplitude variation of the small-scale fading distribution in the absence and presence of human bodies. The results show that the small-scale fading statistics are best described by Weibull distribution and the two parameters of the distribution that determine the shape and the scale of the distribution depend on whether or not human bodies exist. We modeled and analyzed two parameters at different excess delays for all environments. Based on the measured small-scale fading distribution, this paper deals with the performance of UWB system using Rake receivers and also compares the performance with the existing channel model. The results suggest that the small-scale fading distribution in the absence and the presence of human bodies in indoor LOS environments should be considered when assessing the performance of UWB systems.

In this paper, the voice signal processing module has been designed using the micro processor for the use of fully implantable middle ear devices (F-IMEHD). The voice signal processing module for F-IMEHD should be designed to compensate for the hearing loss of hearing impaired person and have the flexibility for compensating various hearing threshold level. So, the voice signal processing module has been designed and implemented to present the various frequency characteristics using the low-power micro processor, MSP430F169. The different voice signal path to the inner ear entrance was considered so that two voice signal would be combined in-phase using an all pass filter with a constant time-delay to improve the vibration of the ossicles.

The growth of the Internet has resulted in an increasing need for personalized information systems. The paper describes an autonomous agent, the Web Robot Agent or WebBot, which integrates with the web and acts as a personal recommendation system that cooperates with the user in order to identify interesting pages. The Apriori algorithm extracts the characteristics of the web pages in the form of association words that are semantically related and mines a bag of association words. Using hybrid components from collaborative filtering and content-based filtering, this hybrid recommendation system can overcome the shortcomings associated with traditional recommendation systems. In this paper, we present an improved recommendation system, which uses the user preference mining through hybrid 2-way filtering. The proposed method was tested on a database, and its effectiveness compared with existent methods was proven in on-line experiments.

This paper presents a hardware design of high throughput, low latency preamble detector for 3GPP LTE physical random access channel (PRACH) receiver. The presented PRACH receiver uses the pipelined structure to improve the throughput of power delay profile (PDP) generation which is executed multiple times during the preamble detection. In addition, to reduce detection latency, we propose an instantaneous preamble detection method for both restricted and unrestricted set. The proposed preamble detection method can detect all existing preambles directly and instantaneously from PDP output while conducting PDP combining for restricted set. The PDP combining enables the PRACH receiver to detect preambles robustly even in severe Doppler effect or frequency error exist. Using proposed method, the worst case preamble detection latency time can be less than 1 ms with 136 MHz clock and the proposed PRACH receiver can be implemented with approximately 237k equivalent ASIC gates count or occupying 30.2% of xc6vlx130t FPGA device.

Recently, wireless multi-hop network using MIMO two-way relaying technique has been attracted much attention owing to its high network efficiency. It is well known that the MIMO two-way multi-hop network (MTMN) can provide its maximum throughput in uniform topology of node location. However, in realistic environments with non-uniform topology, network capacity degrades severely due to unequal link quality. Furthermore, the end-to-end capacity also degrades at high SNR due to far (overreach) interference existing in multi-hop relay scenarios. In this paper, we focus on several power allocation schemes to improve the end-to-end capacity performance of MTMN with non-uniform topology and far interference. Three conventional power allocation schemes are reformulated and applied under the system model of MTMN. The first two are centralized methods, i.e., Eigenvector based Power Allocation (EPA) which employs linear algebra and Optimal Power Allocation (OPA) using convex optimization. The last one is Distributed Power Allocation (DPA) using game theory. It is found from numerical analyses that the power allocation schemes are effective for MTMN in terms of end-to-end capacity improvement, especially in non-uniform node arrangement and at high SNR.

We have investigated the effect of deoxyribonucleic acid (DNA) adsorption on a graphene field-effect-transistor (FET) device. We have used graphene which is grown on a Ni substrate by chemical vapour deposition. The Raman spectra of our graphene indicate its high quality, and also show that it consists of only a few layers. The current-voltage characteristics of our bare graphene strip FET show a hole conduction behavior, and the gate sensitivity of 0.0034 µA/V, which is reasonable with the size of the strip (510 µm2). After the adsorption of 30 base pairs single-stranded poly (dT) DNA molecules, the conductance and gate operation of the graphene FET exhibit almost 11% and 18% decrease from those of the bare graphene FET device. The observed change may suggest a large sensitivity for a small enough (nm size) graphene strip with larger semiconducting property.

Recently, a number of concurrency control algorithms have been proposed for multidatabase system (MDBS) concurrency control methods (CCMs) and the most challenging issue of them has been a concern about how to ensure global serializability (GSR). In this paper, we examine two concurrency control algorithms of MDBS through simulation approach: optimistic ticket method (OTM) and global ticket method (GTM). In historical note, OTM is known to be the first practical solution, since this approach ensures GSR by way of automatically resolving indirect conflicts among global transactions without making any restrictions on local CCMs. However, OTM is expected to yield poor performance since it enforces all global transactions to take a local ticket which causes direct conflicts between them. In GTM, the global transaction manager in an MDBS assigns a global ticket to global transactions rather than accessing a local ticket as in OTM. Our experimental results showed that GTM outperforms OTM in cases that short timeout values are given. However, in case that the timeout value relatively becomes long, our results demonstrated that OTM outperforms GTM.

Footprint assembly was proposed to reduce the blurriness of texture mapped image by mipmapping. Even though it can improve the quality of texture mapped image, there are yet blurring due to the limitation of it's filter kernel. This paper proposes a novel texture filtering, called adaptive footprint assembly (AFA), to overcome the limitation of footprint assembly. The proposed method greatly improves the quality of texture mapped images.