A 5 GHz LC-VCO frequency synthesizer for unlicensed band of WiMAX

This paper presents a low power and low phase noise CMOS integer-N frequency synthesizer based on the charge-pump Phase Locked Loop (PLL) topology. The frequency synthesizer can be used for IEEE 802.16 unlicensed band of WiMAX (World Interoperability for Microwave Access). The operation frequency of the proposed design is ranged from 5.13 to 5.22 GHz. The proposed Voltage-Controlled Oscillator (VCO) achieves low power consumption and low phase noise. The high speed divider is implemented by an optimal extended true single phase clock (E-TSPC) prescaler. It can achieve higher operating frequency and lower power consumption. A new frequency divider is also proposed to eliminate the hardware overhead of the S counter in the conventional programmable divider. The proposed frequency synthesizer consists of a phase-frequency detector (PFD), a charge pump, a low-pass loop filter, a VCO, and a frequency divider. The simulated phase noise of the proposed VCO is −121.6 dBc/Hz at 1 MHz offset from the carrier frequency. The proposed frequency synthesizer consumes 13.1 mW. The chip with an area of 1.048 × 1.076 mm² is fabricated in a TSMC 0.18 μm CMOS 1P6M technology process.     

Active noise control in a forced-air cooling system

This paper discusses the design methodology for the active noise control of sound disturbances in a forced-air cooling system. The active sound cancellation algorithm uses the framework of output-error based optimization of a linearly parametrized filter for feedforward sound compensation to select microphone location and demonstrate the effectiveness of active noise cancellation in a small portable data projector. Successful implementation of the feedforward based active noise controller on a NEC LT170 data projector shows a 20–40 dB reduction per frequency point in the spectrum of external noise of the forced-air cooling system can be obtained over a broad frequency range from 1 to 5 kHz. A total noise reduction (unweighted) of 9.3 dB is achieved.     

Integrated chip-size antennas for wireless microsystems: Fabrication and design considerations

This paper reports on fabrication and design considerations of an integrated folded shorted-patch chip-size antenna for applications in short-range wireless microsystems and operating inside the 5–6 GHz ISM band. Antenna fabrication is based on wafer-level chip-scale packaging (WLCSP) techniques and consists of two adhesively bonded glass wafers with patterned metallization and through-wafer electrical interconnects. Via formation in glass substrates is identified as the key fabrication step. Various options for via formation are compared and from these, a 193 nm excimer laser ablation is selected for fabrication of the antenna demonstrator. The fabricated antenna has dimensions of 4 mm × 4 mm × 1 mm, measured operating frequency of 5.05 GHz with a bandwidth of ∼200 MHz at the return loss of −10 dB and a simulated radiation efficiency of 60% were achieved.     

Unsupervised feature selection using swarm intelligence and consensus clustering for automatic fault detection and diagnosis in Heating Ventilation and Air Conditioning systems

Various sensory and control signals in a Heating Ventilation and Air Conditioning (HVAC) system are closely interrelated which give rise to severe redundancies between original signals. These redundancies may cripple the generalization capability of an automatic fault detection and diagnosis (AFDD) algorithm. This paper proposes an unsupervised feature selection approach and its application to AFDD in a HVAC system. Using Ensemble Rapid Centroid Estimation (ERCE), the important features are automatically selected from original measurements based on the relative entropy between the low- and high-frequency features. The materials used is the experimental HVAC fault data from the ASHRAE-1312-RP datasets containing a total of 49 days of various types of faults and corresponding severity. The features selected using ERCE (Median normalized mutual information (NMI) = 0.019) achieved the least redundancies compared to those selected using manual selection (Median NMI = 0.0199) Complete Linkage (Median NMI = 0.1305), Evidence Accumulation K-means (Median NMI = 0.04) and Weighted Evidence Accumulation K-means (Median NMI = 0.048). The effectiveness of the feature selection method is further investigated using two well-established time-sequence classification algorithms: (a) Nonlinear Auto-Regressive Neural Network with eXogenous inputs and distributed time delays (NARX-TDNN); and (b) Hidden Markov Models (HMM); where weighted average sensitivity and specificity of: (a) higher than 99% and 96% for NARX-TDNN; and (b) higher than 98% and 86% for HMM is observed. The proposed feature selection algorithm could potentially be applied to other model-based systems to improve the fault detection performance.     

Hybrid wireless sensor network for building energy management systems based on the 2.4 GHz and 400 MHz bands

In this paper, a hybrid wireless sensor network (WSN) system is considered and implemented for the building energy management systems. Characteristics of the radios, which are based on the 2.4 GHz and 400 MHz bands, respectively, are analyzed for the building environments. For battery-operated portable sensors, narrow-bandwidth radios of the 400 MHz band are employed in a star connection between their parent nodes. Between the parent nodes, a mesh network is constructed for an efficient and fast data transmission based on the wide-bandwidth radios of the 2.4 GHz band. The hybrid WSN system is implemented and tested for a building environment and provides a reliable wireless communication link for gathering sensing data.     

Inclusion complexation of pinostrobin with various cyclodextrin derivatives

Pinostrobin (PNS) is one of the important flavonoids and can be abundantly found in the rhizomes of fingerroot (Boesenbergia rotrunda) and galangal (Alpinia galangal and Alpinia officinarum), the herbal basis of Southeast Asian cooking. Similar to other flavonoids, PNS exhibits anti-oxidative, anti-inflammatory and anti-cancer properties. However, this compound has an extremely low water solubility that limits its use in pharmaceutical applications. Beta-cyclodextrin (βCD) and its derivatives, 2,6-dimethyl-βCD (2,6-DMβCD) and the three hydroxypropyl-βCDs (2-HPβCD, 6-HPβCD and 2,6-DHPβCD), have unique properties that enhance the stability and solubility of such low-soluble guest molecules. In the present study, molecular dynamics simulations were applied to investigate the dynamics and stability of PNS inclusion complexes with βCD and its derivatives (2,6-DMβCD, 2,6-DHPβCD, 2-HPβCD and 6-HPβCD). PNS was able to form complexes with βCD and all four of its derivatives by either the chromone (C-PNS) or phenyl (P-PNS) ring dipping toward the cavity. According to the molecular mechanics-generalized Born surface area binding free energy values, the stability of the different PNS/βCD complexes was ranked as 2,6-DHPβCD > 2,6-DMβCD > 2-HPβCD > 6-HPβCD > βCD. These theoretical results were in good agreement with the stability constants that had been determined by the solubility method.     

Efficient multicast schemes for 3-D Networks-on-Chip

3-D Networks-on-Chip (NoCs) have been proposed as a potent solution to address both the interconnection and design complexity problems facing future System-on-Chip (SoC) designs. In this paper, two topology-aware multicast routing algorithms, Multicasting XYZ (MXYZ) and Alternative XYZ (AL + XYZ) algorithms in supporting of 3-D NoC are proposed. In essence, MXYZ is a simple dimension order multicast routing algorithm that targets 3-D NoC systems built upon regular topologies. To support multicast routing in irregular regions, AL + XYZ can be applied, where an alternative output channel is sought to forward/replicate the packets whenever the output channel determined by MXYZ is not available. To evaluate the performance of MXYZ and AL + XYZ, extensive experiments have been conducted by comparing MXYZ and AL + XYZ against a path-based multicast routing algorithm and an irregular region oriented multiple unicast routing algorithm, respectively. The experimental results confirm that the proposed MXYZ and AL + XYZ schemes, respectively, have lower latency and power consumption than the other two routing algorithms, meriting the two proposed algorithms to be more suitable for supporting multicasting in 3-D NoC systems. In addition, the hardware implementation cost of AL + XYZ is shown to be quite modest.     

Ultra high performance planar InGaAs PIN photodiodes for high speed optical fiber communication

This paper reports a front-illuminated planar InGaAs PIN photodiode with very low dark current, very low capacitance and very high responsivity on S-doped InP substrate. The presented device which has a thick absorption layer of 2.92 μm and a photosensitive area 73 μm in diameter exhibited the high performance of a very low capacitance of 0.47 pF, a very low dark current of 0.041 nA, a very high responsivity of 0.99 A/W (79% quantum efficiency) at λ = 1.55 μm, the 3 dB bandwidths of 6.89 GHz (−5 V), 7.48 GHz (−12 V) for bare chips and 4.48 GHz (−5 V), 5.02 GHz (−12 V) for the devices packaged in TO can, respectively. Furthermore, the developed PIN photodiodes possess high breakdown voltage of less than −25 V.     

Determination of optimal parameters for bilateral filter in brain MR image denoising

Noise elimination is an important pre-processing step in magnetic resonance (MR) images for clinical purposes. In the present study, as an edge-preserving method, bilateral filter (BF) was used for Rician noise removal in MR images. The choice of BF parameters affects the performance of denoising. Therefore, as a novel approach, the parameters of BF were optimized using genetic algorithm (GA). First, the Rician noise with different variances (σ = 10, 20, 30) was added to simulated T1-weighted brain MR images. To find the optimum filter parameters, GA was applied to the noisy images in searching regions of window size [3 × 3, 5 × 5, 7 × 7, 11 × 11, and 21 × 21], spatial sigma [0.1–10] and intensity sigma [1–60]. The peak signal-to-noise ratio (PSNR) was adjusted as fitness value for optimization.After determination of optimal parameters, we investigated the results of proposed BF parameters with both the simulated and clinical MR images. In order to understand the importance of parameter selection in BF, we compared the results of denoising with proposed parameters and other previously used BFs using the quality metrics such as mean squared error (MSE), PSNR, signal-to-noise ratio (SNR) and structural similarity index metric (SSIM). The quality of the denoised images with the proposed parameters was validated using both visual inspection and quantitative metrics. The experimental results showed that the BF with parameters proposed by us showed a better performance than BF with other previously proposed parameters in both the preservation of edges and removal of different level of Rician noise from MR images. It can be concluded that the performance of BF for denoising is highly dependent on optimal parameter selection.     

Experimental study and thermodynamic modelling of the B-Fe-Mn ternary system

This work is focused on an experimental study of phase equilibria in the B-Fe-Mn ternary system combined with a CALPHAD theoretical analysis with the aim of creating a reliable theoretical thermodynamic dataset for calculation of the phase diagram of the ternary system. Boron is modelled as an interstitial element in all solid solutions of Fe and Mn. In the experimental study, B-Mn-Fe alloys were prepared and heat-treated at 873 K for 90 days/2160 h and at 1223 K for 60 days/1440 h. Following heat treatment, the phase equilibria and composition of the coexisting phases were determined using scanning electron microscopy and X-ray diffraction analysis. The experimental results obtained, together with experimental results collected from the literature, were used in the optimization of the thermodynamic parameters by using the CALPHAD method. The result of this work is an optimized thermodynamic dataset for the B-Fe-Mn ternary system allowing the phase diagram and thermodynamic properties to be calculated.     

Silicon microphone development and application

This paper gives an overview of the development of Silicon microphones fabricated in a standard BiCMOS process line of Infineon. MEMS development results in reliable processes for high sensitivity poly-silicon membranes. Microphones with sensitivity up to −39 dB V/Pa at 2 V bias and a signal to noise ratio of up to 65 dB(A) are presented. The impact of packaging on the product design is described. As an example a directional microphone with cardioid response and backward noise suppression of 19 dB is described.     

An enhanced one-dimensional SPIHT algorithm and its implementation for TV systems

In general, to achieve high compression efficiency, a 2D image or a 2D block is used as the compression unit. However, 2D compression requires a large memory size and long latency when input data are received in a raster scan order that is common in existing TV systems. To address this problem, a 1D compression algorithm that uses a 1D block as the compression unit is proposed. 1D set partitioning in hierarchical trees (SPIHT) is an effective compression algorithm that fits the encoded bit length to the target bit length precisely. However, the 1D SPIHT can have low compression efficiency because 1D discrete wavelet transform (DWT) cannot make use of the redundancy in the vertical direction. This paper proposes two schemes for improving compression efficiency in the 1D SPIHT. First, a hybrid coding scheme that uses different coding algorithms for the low and high frequency bands is proposed. For the low-pass band, a differential pulse code modulation–variable length coding (DPCM–VLC) is adopted, whereas a 1D SPIHT is used for the high-pass band. Second, a scheme that determines the target bit length of each block by using spatial correlation with a minimal increase in complexity is proposed. Experimental results show that the proposed algorithm improves the average peak signal to noise ratio (PSNR) by 2.97 dB compared with the conventional 1D SPIHT algorithm. With the hardware implementation, the throughputs of both encoder and decoder designs are 6.15 Gbps, and gate counts of encoder and decoder designs are 42.8 K and 57.7 K, respectively.     

A novel adaptive cuckoo search algorithm for intrinsic discriminant analysis based face recognition

This paper presents a novel adaptive cuckoo search (ACS) algorithm for optimization. The step size is made adaptive from the knowledge of its fitness function value and its current position in the search space. The other important feature of the ACS algorithm is its speed, which is faster than the CS algorithm. Here, an attempt is made to make the cuckoo search (CS) algorithm parameter free, without a Levy step. The proposed algorithm is validated using twenty three standard benchmark test functions. The second part of the paper proposes an efficient face recognition algorithm using ACS, principal component analysis (PCA) and intrinsic discriminant analysis (IDA). The proposed algorithms are named as PCA + IDA and ACS–IDA. Interestingly, PCA + IDA offers us a perturbation free algorithm for dimension reduction while ACS + IDA is used to find the optimal feature vectors for classification of the face images based on the IDA. For the performance analysis, we use three standard face databases—YALE, ORL, and FERET. A comparison of the proposed method with the state-of-the-art methods reveals the effectiveness of our algorithm.     

Impact of Ultra Wide Band emission on WiMAX systems at 2.5 and 3.5 GHz

In this work, results of an analytical analysis to assess the effect of Ultra Wide Band (UWB) emissions on the Worldwide Interoperability for Microwave Access system (WiMAX) are presented. The WiMAX range is evaluated with and without the UWB interference. Free space propagation model is used to calculate the UWB signal power that interferes with WiMAX systems. It is shown that, for the case of single UWB transmitter, WiMAX system can easily tolerate UWB interference when the UWB EIRP is ?83 dBm/MHz or less for a distance between the UWB transmitter and the WiMAX receiver of 1 m or higher at 3.5 GHz frequency in order to have only 5% range reduction. To make this possible, multi band UWB should not transmit in the first and the second bands. This will have a detrimental effect on UWB technology. For 2.5 GHz WiMAX, the range reduction will be 5% when the UWB EIRP is ?87 dBm/MHz.     

Development of a wide-tuning range and high Q variable capacitor using metal-based surface micromachining process

This study aims to improve the tuning range and quality-factor (Q) of micro variable capacitors for wireless communication applications. A suspending 0.5 μm-thick gold thin-plate with two-gap structure in one-to-three ratio of spacing is designed for the maximization of tuning range. To enhance effectively the flexural rigidity of top metal-plate and improve further the tuning range of the varactor, a double-cross-type microstructure with two vertical fixed-fixed beam springs and four horizontal fixed-guided cantilever beams is introduced. Besides, a glass substrate (Corning 7740) was used to reduce substantially the power dissipation and improve the Q-factor of variable capacitor. The new glass-based double-cross-type micro variable capacitor has demonstrated many superior performances, including the wide-tuning range (2100%, at 1.0 MHz with 6.0 V), the moderate capacitance (0.56 pF, at 2.4 GHz and without DC bias), 6.5 V pull-in voltage, and the high Q-factor (40.6, at 2.4 GHz). These characteristics approximately match with the theoretical derivation or simulated results from Agilent-ADS, Ansoft-HFSS, and IntelliSuite software.     

Passive single chip wireless microwave pressure sensor

A novel micromachined passive wireless pressure sensor is presented. The device consists of a tuned circuit operating at 10 GHz fabricated on to a SiO₂ membrane, supported on a silicon wafer. A pressure difference across the membrane causes it to deflect so that an antenna circuit detunes. The circuit is remotely interrogated to read off the sensor data wirelessly. The chip area is 5 mm × 4 mm and the membrane area is 2 mm² with a thickness of 4 μm. Two on-chip passive resonant circuits were investigated: a meandered dipole and a zigzag antenna. Both have a physical length of 4.25 mm. The sensors show a shift in their resonant frequency in response to changing pressure of 10.28–10.27 GHz for the meandered dipole, and 9.61–9.58 GHz for the zigzag antenna. The sensitivities of the meandered dipole and zigzag sensors are 12.5 kHz/mbar and 16 kHz/mbar respectively.     

Search space reduction in QoS routing

To provide real-time service or engineer constrained-based paths, networks require the underlying routing algorithm to be able to find low-cost paths that satisfy given quality-of-service constraints. However, the problem of constrained shortest (least-cost) path routing is known to be NP-hard, and some heuristics have been proposed to find a near-optimal solution. However, these heuristics either impose relationships among the link metrics to reduce the complexity of the problem which may limit the general applicability of the heuristic, or are too costly in terms of execution time to be applicable to large networks. In this paper, we focus on solving the delay-constrained minimum-cost path problem, and present a fast algorithm to find a near-optimal solution. This algorithm, called delay-cost-constrained routing (DCCR), is a variant of the k-shortest-path algorithm. DCCR uses a new adaptive path weight function together with an additional constraint imposed on the path cost, to restrict the search space. Thus, DCCR can return a near-optimal solution in a very short time. Furthermore, we use a variant of the Lagrangian relaxation method proposed by Handler and Zang [Networks 10 (1980) 293] to further reduce the search space by using a tighter bound on path cost. This makes our algorithm more accurate and even faster. We call this improved algorithm search space reduction + DCCR (SSR + DCCR). Through extensive simulations, we confirm that SSR + DCCR performs very well compared to the optimal but very expensive solution.     

Hexagon-based all-quadrilateral mesh generation with guaranteed angle bounds

In this paper, we present a novel hexagon-based mesh generation method which creates all-quadrilateral (all-quad) meshes with guaranteed angle bounds and feature preservation for arbitrary planar domains. Given any planar curves, an adaptive hexagon-tree structure is constructed by using the curvature of the boundaries and narrow regions. Then a buffer zone and a hexagonal core mesh are created by removing elements outside or around the boundary. To guarantee the mesh quality, boundary edges of the core mesh are adjusted to improve their formed angles facing the boundary, and two layers of quad elements are inserted in the buffer zone. For any curve with sharp features, a corresponding smooth curve is firstly constructed and meshed, and then another layer of elements is inserted to match the smooth curve with the original one. It is proved that for any planar smooth curve all the element angles are within [60° ? ε, 120° + ε] (ε ? 5°). We also prove that the scaled Jacobians defined by two edge vectors are in the range of [sin (60° ? ε),  sin 90°], or [0.82, 1.0]. The same angle range can be guaranteed for curves with sharp features, with the exception of small angles in the input curve. Furthermore, an approach is introduced to match the generated interior and exterior meshes with a relaxed angle range, [30°, 150°]. We have applied our algorithm to a set of complicated geometries, including the China map, the Lake Superior map, and a three-component air foil with sharp features. In addition, all the elements in the final mesh are grouped into five types, and most elements only need a few flops to construct the stiffness matrix for finite element analysis. This will significantly reduce the computational time and the required memory during the stiffness matrix construction.     

A high-throughput and high-capacity IPv6 routing lookup system

With the growing number of routing entries, IP routing lookup has become the major performance bottleneck in backbone routers. In this paper, a complete hardware-based routing lookup system is proposed to achieve high-throughput and high-capacity for IPv6. The proposed system is a cache-centric, hash-based architecture that contains a routing lookup application specific integrated circuit (ASIC) and a memory set. A hash function is used to reduce lookup time for the routing table and ternary content addressable memory (TCAM) effectively resolves the collision problem. The gate count of the ASIC, excluding the binary content addressable memory (BCAM), is about 5306 gates, using an in-house 0.18 μm CMOS single-poly six-metal standard cell library. The results of post-layout simulations show that the ASIC operates in 3.6 ns so that the routing lookup system approaches 260 Mega lookups per second (Mlps), which is sufficient for 100 Gbps networks. The memory density is good, with each routing entry requiring only 64 bits. Moreover, the routing table only needs 10.24 KB on-chip BCAM, 20.04 KB off-chip TCAM and 29.29 MB DRAM for 3.6 M routing entries in the proposed system.     

Vibrational analysis of graphene based nanostructures

This paper deals with the molecular mechanics simulations of graphene nanostructures and their vibration behavior for potential applications on nano-electronics and nanocomposites. The fundamental frequencies for CNTs range from 10 to 250 GHz and 100 to 1000 GHz for the cantilevered and bridged conditions, respectively. As the ratio L/d increases the fundamental frequency decreases, as expected. A decrease on fundamental frequencies with the bending waviness was noticed for all conditions. The mode shape for bent carbon nanotubes seems to be a superposition of the vibration mode and the bending mode for the zigzag configuration. Multi-layered graphene nanosheets were also investigated. The fundamental frequencies ranged from 50 to 150 GHz, with an odd/even shape mode switch.