The fringe field effects of nano-electromechanical (NEM) nonvolatile memory cells have been investigated analytically for the accurate evaluation of NEM memory cells. As the beam width is scaled down, fringe field effect becomes more severe. It has been observed that pull-in, release and hysteresis voltage decrease more than our prediction. Also, the fringe field on cell characteristics has been discussed.
Min-Chul SUN Hyun Woo KIM Sang Wan KIM Garam KIM Hyungjin KIM Byung-Gook PARK
As an add-on device option for the ultra-low power CMOS technology, the double-gated vertical-channel Tunnel Field-Effect Transistors (TFETs) of different source configurations are comparatively studied from the perspectives of fabrication and current drivability. While the top-source design where the source of the device is placed on the top of the fin makes the fabrication and source engineering much easier, it is more susceptible to parasitic resistance issue. The bottom-source design is difficult to engineer the tunneling barrier and may require a special replacement technique. Examples of the schemes to engineer the tunneling barrier for the bottom-source TFET are suggested. A TCAD simulation study on the bottom-source devices shows that both the parasitic resistance of source region and the current enhancement mechanism by field coupling need be carefully considered in designing the source.
Kenjiro SUGIMOTO Koji INOUE Yoshimitsu KUROKI Sei-ichiro KAMATA
This paper presents a color-based method for medicine package recognition, called a linear manifold color descriptor (LMCD). It describes a color distribution (a set of color pixels) of a color package image as a linear manifold (an affine subspace) in the color space, and recognizes an anonymous package by linear manifold matching. Mainly due to low dimensionality of color spaces, LMCD can provide more compact description and faster computation than description styles based on histogram and dominant-color. This paper also proposes distance-based dissimilarities for linear manifold matching. Specially designed for color distribution matching, the proposed dissimilarities are theoretically appropriate more than J-divergence and canonical angles. Experiments on medicine package recognition validates that LMCD outperforms competitors including MPEG-7 color descriptors in terms of description size, computational cost and recognition rate.
We have investigated the low-power circuit applicability of hetero-gate-dielectric tunneling field-effect transistors (HG TFETs). Based on the device-level comparison of HG, SiO2-only and high-k-only TFETs, their circuit performance and energy consumption have been discussed. It has been shown that HG TFETs can deliver 14400x higher performance than the SiO2-only TFETs and 17x higher performance than the high-k-only TFETs due to its higher on current and lower capacitance at the same static power, same power supply. It has been revealed that HG TFETs have better voltage scalability than the others. It is because HG TFETs dissipate only 8% of energy consumption of SiO2-only TFETs and 17% of that of high-k-only TFETs under the same performance condition.
Given an odd prime q and an integer m ≤ q, an array-based parity-check matrix H(m,q) can be constructed for a quasi-cyclic low-density parity-check (LDPC) code C(m,q). For m=4 and q ≥ 11, we prove the stopping distance of H(4,q) is 10, which is equal to the minimum Hamming distance of the associated code C(4,q). In addition, a tighter lower bound on the stopping distance of H(m,q) is also given for m > 4 and q ≥ 11.
Electrical performances of gate-all-around (GAA) tunneling field-effect transistors (TFETs) based on a silicon germanium (Si1-xGex) layer have been investigated in terms of subthreshold swing (SS), on/off current ratio, on-state current (Ion). Cut-off frequency (fT) and maximum oscillation frequency (fmax) were demonstrated from small-signal parameters such as effective gate resistance (Rg), gate-drain capacitance (Cgd), and transconductance (gm). According to the technology computer-aided design (TCAD) simulation results, the current drivability, fT, and fmax of GAA TFETs based on Si1-xGex layer were higher than those of GAA TFETs based on silicon. The simulated devices had 60 nm channel length and 10 nm channel radius. A GAA TFET with x = 0.4 had maximum Ion of 51.4 µA/µm, maximum fT of 72 GHz, and maximum fmax of 610 GHz. Additionally, improvements of performance at the presented device with PNPN junctions were demonstrated in terms of Ion, SS, fT, and fmax. When the device was designed with x = 0.4 and n+ layer width (Wn) = 6 nm, it shows Ion of 271 µA/µm, fT of 245 GHz, and fmax of 1.49 THz at an operating bias (VGS = VDS = 1.0 V).
Nobuharu KAMI Teruyuki BABA Takashi YOSHIKAWA Hiroyuki MORIKAWA
We study the properties of information dissemination over location-aware gossiping networks leveraging location-based real-time communication applications. Gossiping is a promising method for quickly disseminating messages in a large-scale system, but in its application to information dissemination for location-aware applications, it is important to consider the network topology and patterns of spatial dissemination over the network in order to achieve effective delivery of messages to potentially interested users. To this end, we propose a continuous-space network model extended from Kleinberg's small-world model applicable to actual location-based applications. Analytical and simulation-based study shows that the proposed network achieves high dissemination efficiency resulting from geographically neutral dissemination patterns as well as selective dissemination to proximate users. We have designed a highly scalable location management method capable of promptly updating the network topology in response to node movement and have implemented a distributed simulator to perform dynamic target pursuit experiments as one example of applications that are the most sensitive to message forwarding delay. The experimental results show that the proposed network surpasses other types of networks in pursuit efficiency and achieves the desirable dissemination patterns.
Xiaoxuan WANG Lei XIE Mimi LU Bin MA Eng Siong CHNG Haizhou LI
In this paper, we propose integration of multimodal features using conditional random fields (CRFs) for the segmentation of broadcast news stories. We study story boundary cues from lexical, audio and video modalities, where lexical features consist of lexical similarity, chain strength and overall cohesiveness; acoustic features involve pause duration, pitch, speaker change and audio event type; and visual features contain shot boundaries, anchor faces and news title captions. These features are extracted in a sequence of boundary candidate positions in the broadcast news. A linear-chain CRF is used to detect each candidate as boundary/non-boundary tags based on the multimodal features. Important interlabel relations and contextual feature information are effectively captured by the sequential learning framework of CRFs. Story segmentation experiments show that the CRF approach outperforms other popular classifiers, including decision trees (DTs), Bayesian networks (BNs), naive Bayesian classifiers (NBs), multilayer perception (MLP), support vector machines (SVMs) and maximum entropy (ME) classifiers.
Takuya KUSAKA Ryuhei YOKOYAMA Toru FUJIWARA
A recursive and efficient method for generating binary vectors in non-increasing order of their likelihood for a set of all binary vectors is proposed. Numerical results on experiments show the effectiveness of this method. Efficient decoding algorithms with simulation results are also proposed as applications of the method.
Satoru AKIYAMA Riichiro TAKEMURA Tomonori SEKIGUCHI Akira KOTABE Kiyoo ITOH
A gated sense amplifier (GSA) consisting of a low-Vt gated preamplifier (LGA) and a high-Vt sense amplifier (SA) is proposed. The gating scheme of the LGA enables quick amplification of an initial cell signal voltage (vS0) because of its low Vt and prevents the cell signal from degrading due to interference noise between data lines. As for a conventional sense amplifier (CSA), this new type of noise causes sensing error, and the noise-generation mechanism was clarified for the first time by analysis of vS0. The high-Vt SA holds the amplified signal and keeps subthreshold current low. Moreover, the gating scheme of the low-Vt MOSFETs in the LGA drives the I/O line quickly. The GSA thus simultaneously achieves fast sensing, low-leakage data holding, and fast I/O driving, even for sub-1-V mid-point sensing. The GSA is promising for future sub-1-V gigabit dynamic random-access memory (DRAM) because of reduced variations in the threshold voltage of MOSFETs; thus, the offset voltage of the LGA is reduced. The effectiveness of the GSA was verified with a 70-nm 512-Mbit DRAM chip. It demonstrated row access time (tRCD) of 16.4 ns and read access (tAA) of 14.3 ns at array voltage of 0.9 V.
Xiaojun SUN Ming JIANG Wei XU Pengcheng ZHU Chunming ZHAO
In this letter, we use the the protograph low-density parity check (LDPC) codes to create bit-interleaved coded modulation (BICM) for the half-duplex decode-and-forward (DF) relay network. The DF relay BICM design problem can be transformed into a problem of rate-compatible BICM design, where the different segments of modulated symbols experience different signal-to-noise ratios (SNRs). To optimize the BICM based on the protograph structure, we use the protograph extrinsic information transfer (EXIT) to evaluate the thresholds of different mapping patterns between the variable nodes and the modulated bits. With this tool, we search for the most efficient mapping pattern of BICM for the half-duplex DF relay network. Our work can achieve significant gains over the existing work.
Andre CAVALCANTE Allan Kardec BARROS Yoshinori TAKEUCHI Noboru OHNISHI
In this letter, a new approach to segment depth-of-field (DoF) images is proposed. The methodology is based on a two-stage model of visual neuron. The first stage is a retinal filtering by means of luminance normalizing non-linearity. The second stage is a V1-like filtering using filters estimated by independent component analysis (ICA). Segmented image is generated by the response activity of the neuron measured in terms of kurtosis. Results demonstrate that the model can discriminate image parts in different levels of depth-of-field. Comparison with other methodologies and limitations of the proposed methodology are also presented.
In this paper, a theoretical analysis of current-controlled (CC-) MOS current mode logic (MCML) is reported. Furthermore, the circuit performance of the CC-MCML with the auto-detection of threshold voltage (Vth) fluctuation is evaluated. The proposed CC-MCML with the auto-detection of Vth fluctuation automatically suppresses the degradation of circuit performance induced by the Vth fluctuations of the transistors automatically, by detecting these fluctuations. When a Vth fluctuation of ± 0.1 V occurs on the circuit, the cutoff frequency of the circuit is increased from 0 Hz to 3.5 GHz by using the proposed CC-MCML with the auto-detection of Vth fluctuation.
In Digital Library (DL) applications, digital book clustering is an important and urgent research task. However, it is difficult to conduct effectively because of the great length of digital books. To do the correct clustering for digital books, a novel method based on probabilistic topic model is proposed. Firstly, we build a topic model named LDAC. The main goal of LDAC topic modeling is to effectively extract topics from digital books. Subsequently, Gibbs sampling is applied for parameter inference. Once the model parameters are learned, each book is assigned to the cluster which maximizes the posterior probability. Experimental results demonstrate that our approach based on LDAC is able to achieve significant improvement as compared to the related methods.
Ji WANG Yuanzhi CHENG Yili FU Shengjun ZHOU Shinichi TAMURA
We describe a multi-step approach for automatic segmentation of the femoral head and the acetabulum in the hip joint from three dimensional (3D) CT images. Our segmentation method consists of the following steps: 1) construction of the valley-emphasized image by subtracting valleys from the original images; 2) initial segmentation of the bone regions by using conventional techniques including the initial threshold and binary morphological operations from the valley-emphasized image; 3) further segmentation of the bone regions by using the iterative adaptive classification with the initial segmentation result; 4) detection of the rough bone boundaries based on the segmented bone regions; 5) 3D reconstruction of the bone surface using the rough bone boundaries obtained in step 4) by a network of triangles; 6) correction of all vertices of the 3D bone surface based on the normal direction of vertices; 7) adjustment of the bone surface based on the corrected vertices. We evaluated our approach on 35 CT patient data sets. Our experimental results show that our segmentation algorithm is more accurate and robust against noise than other conventional approaches for automatic segmentation of the femoral head and the acetabulum. Average root-mean-square (RMS) distance from manual reference segmentations created by experienced users was approximately 0.68 mm (in-plane resolution of the CT data).
Chunyi SONG Mohammad Azizur RAHMAN Hiroshi HARADA
This paper proposes a sensing method for TV signals of DVB-T standard to realize effective TV White Space (TVWS) Communication. In the TVWS technology trial organized by the Infocomm Development Authority (iDA) of Singapore, with regard to the sensing level and sensing time, detecting DVB-T signal at the level of -120 dBm over an 8 MHz channel with a sensing time below 1 second is required. To fulfill such a strict sensing requirement, we propose a smart sensing method which combines feature detection and energy detection (CFED), and is also characterized by using dynamic threshold selection (DTS) based on a threshold table to improve sensing robustness to noise uncertainty. The DTS based CFED (DTS-CFED) is evaluated by computer simulations and is also implemented into a hardware sensing prototype. The results show that the DTS-CFED achieves a detection probability above 0.9 for a target false alarm probability of 0.1 for DVB-T signals at the level of -120 dBm over an 8 MHz channel with the sensing time equals to 0.1 second.
Teng LONG Le ZHENG Yang LI Xiaopeng YANG
The double threshold detecting strategy is widely used for spatially distributed target detection in practical systems. However, the detector is limited in terms of robustness and effectiveness. In this paper, an improved double threshold detector is proposed that avoids these shortcomings. In the proposed detector, the energy in range cells that exceed the first threshold is accumulated and then the output of the accumulator is compared with the second threshold for detection. The threshold selection strategy is derived to guarantee the constant false-alarm rate (CFAR) property. A simulation shows that the proposed detector is superior to the conventional approach in terms of both robustness and effectiveness.
Masanori HIROTOMO Masami MOHRI Masakatu MORII
In the analysis of maximum-likelihood decoding performance of low-density parity-check (LDPC) codes, the weight distribution is an important factor. We presented a probabilistic method for computing the weight distribution of LDPC codes, and showed results of computing the weight distribution of several LDPC codes. In this paper, we improve our previously presented method and propose a probabilistic computation method with reliability for the weight distribution of LDPC codes. Using the proposed method, we can determine the weight distribution with small failure probability.
Changsheng ZHOU Yuebin HUANG Shuangqu HUANG Yun CHEN Xiaoyang ZENG
Based on Turbo-Decoding Message-Passing (TDMP) and Normalized Min-Sum (NMS) algorithm, an area efficient LDPC decoder that supports both structured and unstructured LDPC codes is proposed in this paper. We introduce a solution to solve the memory access conflict problem caused by TDMP algorithm. We also arrange the main timing schedule carefully to handle the operations of our solution while avoiding much additional hardware consumption. To reduce the memory bits needed, the extrinsic message storing strategy is also optimized. Besides the extrinsic message recover and the accumulate operation are merged together. To verify our architecture, a LDPC decoder that supports both China Multimedia Mobile Broadcasting (CMMB) and Digital Terrestrial/ Television Multimedia Broadcasting (DTMB) standards is developed using SMIC 0.13 µm standard CMOS process. The core area is 4.75 mm2 and the maximum operating clock frequency is 200 MHz. The estimated power consumption is 48.4 mW at 25 MHz for CMMB and 130.9 mW at 50 MHz for DTMB with 5 iterations and 1.2 V supply.
Chanho YOON Hoojin LEE Joonhyuk KANG
A new approach for encoding one class of quasi-cyclic low-density parity-check (QC-LDPC) codes is proposed. The proposed encoding method is applicable to parity-check matrices having dual-diagonal parity structure with single column of weight three in the parity generation region. Instead of finding the parity bits directly, the proposed method finds parity bits through vector correction. While the proposed LDPC encoding scheme is readily applicable to matrices defined in the IEEE physical layer standards, the computational complexity of the post processing operation for extraction of correction vector requires less effort than solving the linear equations involved with finding the parity bit as proposed by Myung et al.