Switch-and-stay combining (SSC) is a simple diversity technique where a single radio frequency (RF) chain is connected to one of several antenna branches and stays there if the channel quality is satisfied or otherwise switches to a new branch. Compared with Selection Combining (SC), SSC requires less overhead in channel estimation and antenna selection feedback. In this paper, we analyze the performance of SSC in a time-correlated flat fading channel and with causal channel state information. We derive the general expressions for the distribution of the output signal-to-noise ratio (SNR), outage rate and average bit error rate (ABER) and then the analytical results are compared with the simulation results under the Jakes Rayleigh fading channel. Our results show that (1) For slowly varying channels, L branch SSC can achieve the full diversity order and the same outage rate as SC; (2) Increasing the number of antenna branches can improve the performance of SSC, however, the gain from adding antennas diminishes quickly as the channel variation speed increases. Moreover, to avoid the complexity in optimizing the fixed threshold, we also propose a simple adaptive SSC scheme which has almost the same ABER as the SSC with optimized fixed threshold.

Multi-valued Model Checking extends classical, two-valued model checking to multi-valued logic such as Quasi-Boolean logic. The added expressivity is useful in dealing with such concepts as incompleteness and uncertainty in target systems, while it comes with the cost of time and space. Chechik and others proposed an efficient reduction from multi-valued model checking problems to two-valued ones, but to the authors' knowledge, no study was done for multi-valued bounded model checking. In this paper, we propose a novel, efficient algorithm for multi-valued bounded model checking. A notable feature of our algorithm is that it is not based on reduction of multi-values into two-values; instead, it generates a single formula which represents multi-valuedness by a suitable encoding, and asks a standard SAT solver to check its satisfiability. Our experimental results show a significant improvement in the number of variables and clauses and also in execution time compared with the reduction-based one.

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.

In this paper, we derive a set of discrete time difference equations that models the spreading process of computer worms such as Code-Red and Slammer, which uses a common strategy called “random scanning” to spread through the Internet. We show that the derived set of discrete time difference equations has an exact relationship with the Kermack and McKendrick susceptible-infectious-removed (SIR) model, which is known as a standard continuous time model for worm spreading.

In this paper, a Schmitt Trigger based 10T SRAM (ST 10T SRAM) cell with the vertical MOSFET is proposed for low supply voltage operation, and its impacts on cell size, stability and speed performance are investigated. The proposed ST 10T SRAM cell with the vertical MOSFET achieves smaller cell size than the ST 10T SRAM cell with the conventional planar MOSFET. Moreover, the proposed SRAM cell realizes large and constant static noise margin (SNM) against bottom node resistance of the vertical MOSFET without any architectural changes from the present 6T SRAM architecture. The proposed SRAM cell also suppresses the degradation of the read time of the ST 10T SRAM cell due to the back-bias effect free characteristic of the vertical MOSFET. The proposed ST 10T SRAM cell with the vertical MOSFET is a superior SRAM cell for low supply voltage operation with a small cell size, stable operation, and fast speed performance with the present 6T SRAM architecture.

In the current study, stress-induced capacitance determined by direct measurement on MOSFETs was compared with that determined by indirect simulation through the delay of CMOS ring oscillators (ROs) fabricated side by side with MOSFETs. External compressive stresses were applied on <110> silicon-on-insulator (SOI) n-/p-MOSFETs with the ROs in a longitudinal configuration. The measured gate capacitance decreased as the compressive stress on SOI increased, which agrees with the result of the capacitance difference between measured and simulated delay of the ROs. The oscillation frequency shift of the ROs should mainly be attributed to oxide capacitance, aside from the change in mobility of the n-/p-MOSFETs. The result suggests that the stress-induced gate capacitance of partially depleted MOSFETs is an important factor for the capacitance shift in a circuit and that ROs can be used in a vehicle to determine mechanical stress-induced gate capacitance in MOSFETs.

In this paper, we fabricated a gate-all-around bandgap-engineered (BE) silicon-oxide-nitride-oxide-silicon (SONOS) and silicon-oxide-high-k-oxide-silicon (SOHOS) flash memory device with a vertical silicon pillar type structure for a potential solution to scaling down. Silicon nitride (Si3N4) and hafnium oxide (HfO2) were used as trapping layers in the SONOS and SOHOS devices, respectively. The BE-SOHOS device has better electrical characteristics such as a lower threshold voltage (VTH) of 0.16 V, a higher gm.max of 0.593 µA/V and on/off current ratio of 5.76108, than the BE-SONOS device. The memory characteristics of the BE-SONOS device, such as program/erase speed (P/E speed), endurance, and data retention, were compared with those of the BE-SOHOS device. The measured data show that the BE-SONOS device has good memory characteristics, such as program speed and data retention. Compared with the BE-SONOS device, the erase speed is enhanced about five times in BE-SOHOS, while the program speed and data retention characteristic are slightly worse, which can be explained via the many interface traps between the trapping layer and the tunneling oxide.

We propose a new three-dimensional (3D) NAND flash memory array having Tied Bit-line and Ground Select Transistor (TiGer) [1]. Channels are stacked in the vertical direction to increase the memory density without the device size scaling. To distinguish stacked channels, a novel operation scheme is introduced instead of adding supplementary control gates. The stacked layers are selected by using ground select line (GSL) and common source line (CSL). Device structure and fabrication process are described. Operation scheme and simulation results for program inhibition are also discussed.

In this paper, a 60 nm-thick ferroelectric film of poly(vinylidene fluoride–trifluoroethylene) on a flexible substrate of aluminum foil was fabricated and characterized. Compared to pristine silicon wafer, Al-foil has very large root-mean-square (RMS) roughness, thus presenting challenges for the fabrication of flat and uniform electronic devices on such a rough substrate. In particular, RMS roughness affects the leakage current of dielectrics, the uniformity of devices, and the switching time in ferroelectrics. To avoid these kinds of problems, a new thin film fabrication method adopting a detach-and-transfer technique has been developed. Here, 'detach' means that the ferroelectric film is detached from a flat substrate (sacrificial substrate), and 'transfer' refers to the process of the detached film being moved onto the rough substrate (main substrate). To characterize the dielectric property of the transferred film, polarization and voltage relationships were measured, and the results showed that a hysteresis loop could be obtained with low leakage current.

In this paper, we designed and fabricated large scale micro-light-emitting-diode (LED) arrays and silicon driver for single chip device for realizing as prototypes of heterogeneous optoelectronic integrated circuits (OEICs). The large scale micro-LED arrays were separated by a dry etching method from mesa structure to 16,384 pixels of 128 128, each with a size of 15 µm in radius. Silicon driver was designed the additional bonding pad on each driving transistor for bonding with micro-LED arrays. Fabricated micro-LED arrays and driver were flip-chip bonded using anisotropic conductive adhesive.

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.

This paper presents the evaluation of the L-2L de-embedding method with misalignment of the contact position. The issues of misalignment of the contact position are investigated. The analysis of misalignment in the L-2L de-embedding procedure is performed. Two comparisons are carried out to verify the error of the L-2L de-embedding method. The calculation percent error in quality factor of the transmission line becomes up to 9.0%, while the transistor S-parameter error percentage becomes up to 21% at 60 GHz in the experimental results. The results show that the measurement errors, caused by the misalignment of the contact position, should be considered carefully.

Effects of conductive defects on unipolar resistive random access memory (RRAM) are investigated in order to reduce the operation current for high density and low power RRAM applications. It is clarified that forming voltage decreases with increasing charged conductive defects which are a source of conductive filament (CF) path and with decreasing cell thickness. Random circuit breaker (RCB) network simulation model which is a dynamic percolation simulation model is used to elucidate these effects. From this simulation results, the optimal cell thickness with sufficient conductive defect shows improved resistive switching characteristics such as low forming voltage, small set voltage distribution and low reset current. From the deep understanding of relationship between conductive defect in various cell thickness and other resistive switching parameters, RRAM with low forming voltage and reset current can be obtained and it will be one of the most promising next generation nonvolatile memories.

We are interested in retrieving video shots or videos containing particular people from a video dataset. Owing to the large variations in pose, illumination conditions, occlusions, hairstyles and facial expressions, face tracks have recently been researched in the fields of face recognition, face retrieval and name labeling from videos. However, when the number of face tracks is very large, conventional methods, which match all or some pairs of faces in face tracks, will not be effective. Therefore, in this paper, an efficient method for finding a given person from a video dataset is presented. In our study, in according to performing research on face tracks in a single video, we also consider how to organize all the faces in videos in a dataset and how to improve the search quality in the query process. Different videos may include the same person; thus, the management of individuals in different videos will be useful for their retrieval. The proposed method includes the following three points. (i) Face tracks of the same person appearing for a period in each video are first connected on the basis of scene information with a time constriction, then all the people in one video are organized by a proposed hierarchical clustering method. (ii) After obtaining the organizational structure of all the people in one video, the people are organized into an upper layer by affinity propagation. (iii) Finally, in the process of querying, a remeasuring method based on the index structure of videos is performed to improve the retrieval accuracy. We also build a video dataset that contains six types of videos: films, TV shows, educational videos, interviews, press conferences and domestic activities. The formation of face tracks in the six types of videos is first researched, then experiments are performed on this video dataset containing more than 1 million faces and 218,786 face tracks. The results show that the proposed approach has high search quality and a short search time.

In this paper, we propose a layered multicast encryption scheme that provides flexible access control to motion JPEG2000 code streams. JPEG2000 generates layered code streams and offers flexible scalability in characteristics such as resolution and SNR. The layered multicast encryption proposal allows a sender to multicast the encrypted JPEG2000 code streams such that only designated groups of users can decrypt the layered code streams. While keeping the layering functionality, the proposed method offers useful properties such as 1) video quality control using only one private key, 2) guaranteed security, and 3) low computational complexity comparable to conventional non-layered encryption. Simulation results show the usefulness of the proposed method.

The development of new technologies has undoubtedly promoted the advances of modern education, among which Virtual Reality (VR) technologies have made the education more visually accessible for students. However, classroom education has been the focus of VR applications whereas not much research has been done in promoting sports education using VR technologies. In this paper, an immersive VR system is designed and implemented to create a more intuitive and visual way of teaching tennis. A scalable system architecture is proposed in addition to the hardware setup layout, which can be used for various immersive interactive applications such as architecture walkthroughs, military training simulations, other sports game simulations, interactive theaters, and telepresent exhibitions. Realistic interaction experience is achieved through accurate and robust hybrid tracking technology, while the virtual human opponent is animated in real time using shader-based skin deformation. Potential future extensions are also discussed to improve the teaching/learning experience.

A workflow net (WF-net for short) is a Petri net which represents a workflow. There are two important subclasses of WF-nets: extended free-choice (EFC for short) and well-structured (WS for short). It is known that most actual workflows can be modeled as EFC WF-nets; Acyclic WS is a subclass of acyclic EFC but has more analysis methods. An acyclic EFC WF-net may be transformed to an acyclic WS WF-net without changing the external behavior of the net. We name such a transformation Acyclic EFC WF-net refactoring. We give a formal definition of acyclic EFC WF-net refactoring problem. We also give a necessary condition and a sufficient condition for solving the problem. Those conditions can be checked in polynomial time. These result in the enhancement of the analysis power of acyclic EFC WF-nets.

In this paper, a logarithmic adaptive quantization projection (LAQP) algorithm for digital watermarking is proposed. Conventional quantization index modulation uses a fixed quantization step in the watermarking embedding procedure, which leads to poor fidelity. Moreover, the conventional methods are sensitive to value-metric scaling attack. The LAQP method combines the quantization projection scheme with a perceptual model. In comparison to some conventional quantization methods with a perceptual model, the LAQP only needs to calculate the perceptual model in the embedding procedure, avoiding the decoding errors introduced by the difference of the perceptual model used in the embedding and decoding procedure. Experimental results show that the proposed watermarking scheme keeps a better fidelity and is robust against the common signal processing attack. More importantly, the proposed scheme is invariant to value-metric scaling attack.

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.

We propose a control-channel-hopping scheme to mitigate scrambling attacks in orthogonal frequency division multiple access (OFDMA) systems. A scrambling attack can be realized by jamming specific frames after monitoring the control channel or by jamming the control channel itself. This letter details a situation in which the control channel is scattered among OFDMA subcarriers. The scattered control channel has a two-dimensional hopping sequence with a mixed order. Simulation results show that our scheme can prevent a jammer from monitoring the control channel and from attacking the channel itself.