Modified Collocation Trefftz Method for the Geometry Boundary Identification Problem of Heat Conduction

In this article, a meshless numerical algorithm is proposed for the boundary identification problem of heat conduction, one kind of inverse problem. In the geometry boundary identification problem, the Cauchy data is given for part of the boundary. The Neumann boundary condition is given for the other portion of the boundary, whose spatial position is unknown. In order to stably solve the inverse problem, the modified collocation Trefftz method, a promising boundary-type meshless method, is adopted for discretizing this problem. Since the spatial position for part of the boundary is unknown, the numerical discretization results in a system of nonlinear algebraic equations (NAEs). Then, the exponentially convergent scalar homotopy algorithm (ECSHA) is used to efficiently obtain the convergent solution of the system of NAEs. The ECSHA is insensitive to the initial guess of the evolutionary process. In addition, the efficiency of the computation is greatly improved, since calculation of the inverse of the Jacobian matrix can be avoided. Four numerical examples are provided to validate the proposed meshless scheme. In addition, some factors that might influence the performance of the proposed scheme are examined through a series of numerical experiments. The stability of the proposed scheme can be proven by adding some noise to the boundary conditions.     

FPGA implementation for 2D discrete wavelet transform

An operator correlation-based algorithm and its VLSI architecture For computing the 2D discrete wavelet transform is presented. The proposed discrete wavelet transform architecture was simulated in Verilog and synthesised with the FPGA compiler. The implementation for the 2D discrete wavelet transform on an FPGA-based design style is described     

Non-ideal effects improvement of SF6 plasma treated hafnium oxide film based on electrolyte-insulator-semiconductor structure for pH-sensor application

A novel HfO₂ thin film with SF₆ plasma treatment as ion selective membrane on electrolyte-insulator-semiconductor structure for pH-sensor was proposed. The sensing characteristics on hydrogen ion detection and the non-ideal effects including drift effect, hysteresis phenomenon, and responses on interference ions were all presented in this article. The results show that the slight increase of pH-sensitivity is achieved and the non-ideal effects are improved after SF₆ plasma treatment. It is finally concluded that the HfO₂ thin film with SF₆ plasma treatment as ion selective membrane is suitable for pH detection and the optimum condition is 5 min for SF₆ plasma treatment.     

Functionalization of multi-walled carbon nanotubes with furan and maleimide compounds through Diels-Alder cycloaddition

Functionalization of multi-walled carbon nanotubes (MWCNTs) is performed through Diels-Alder (DA) reaction, using either furfuryl alcohol (a diene) or N-(4-hydroxyphenyl)maleimide (NHMI, a dienophile) as a functionalization agent. The structures of the functionalized MWCNTs are characterized with Fourier-transform infrared spectroscopy and Raman spectroscopy. Thermogravimetric analysis results also demonstrate the presence of organic portions of the functionalized MWCNTs. The DA reaction is further applied to incorporate polymer chains onto MWCNT surfaces, using a polyamide with maleimide pendent groups. Transmission electron microscopy images show the presence of a polymer layer of about 2-5 nm around the polymer modified MWCNTs.     

Comparing the task effectiveness of instant messaging and electronic mail for geographically dispersed teams in Taiwan

To improve task effectiveness of geographically dispersed teams, media selection approaches a complex issue involving media features and user characteristics. This study compares user perceptions about task effectiveness between instant messengers (IM) and e-mail (EM). Using a field experiment, the design contrasted teams using EM with teams using IM. Thirty-four teams of two graduate students were enrolled as participants from five universities in Taiwan. Two people were separated geographically and had to communicate accordingly. Results indicate that IM-supported teams generated more ideas and task success. However, no significant difference was found in task difficulty between the IM and EM users.     

An innovative scheme for increasing connectivity and life of ZigBee networks

ZigBee networks based on the IEEE 802.15.4 standard are designed for wireless sensor and control networks with low-cost, low-power consumption, and low-data rate. To join in a ZigBee network with the tree topology, the hardware requirement of a device is simple and low threshold. However, a device may become an isolated node due to constraints of configuration parameters in the ZigBee network. To decrease isolated nodes, we propose an approach called Enhanced Connectivity Scheme for the ZigBee network. This scheme can efficiently reconstruct parts of the network to let more devices join, and hence increase the join ratio. Experimental results show that our method can efficiently improve the connectivity of ZigBee networks. In this paper, we also propose a swapping method to extend the life of the ZigBee network. The objective of swapping is to balance the energy consumption of the nodes. Experimental results show that the swapping scheme can increase the life of the network compared to the ZigBee standard operation by 50%. We provide an innovative solution for increasing connectivity and life of the network to ZigBee designs.     

10-Gb/s modulator drivers with local feedback networks

A novel intrinsic collector-base capacitance (C/sub CB/) feedback network (ICBCFN) was incorporated into the conventional cascode and series-connected voltage balancing (SCVB) circuit configurations to implement 10-Gb/s modulator drivers. The drivers fabricated in 0.35-/spl mu/m SiGe BiCMOS process could generate 9 V/sub PP/ differential output swings with rise/fall time of less than 29 ps. Also, the ICBCFN was modified as an intrinsic drain-gate capacitance feedback network (IDGCFN) to implement drivers with differential output swing of 8 V/sub PP/ in 0.18-/spl mu/m CMOS process. The power consumption is as low as 0.6 W. The present work shows that the driving capability is greater than that of the currently reported silicon-based drivers.     

Tailoring of a Piezo-Photo-Thermal Solar Evaporator for Simultaneous Steam and Power Generation

Water and electricity shortages constitute a global energy crisis that cannot be ignored. The sun is an unlimited source of energy, and oceans provide abundant water and renewable energy resources. In this study, poly(vinylidene fluoride) (PVDF)/graphene solar evaporator membranes are fabricated for simultaneous freshwater production and power generation. Graphene addition transformed the PVDF crystal from the α-phase to the piezoelectric self-assembly β-phase. The resulting membrane is used to convert the mechanical energy of waves to electrical energy. The membrane has an output voltage of 2.6 V (±1.3 V) and an energy density of 2.11 Wm⁻² for 1 Hz simulated waves, which are higher than values reported in the literature. The stacked graphene and polymer formed a wood-lumens-like mesoporous structure with a photothermal effect. Under one sun illumination, the water production rate is 1.2 kg m⁻² h⁻¹, and the solar-thermal energy conversion efficiency is 84%. Finally, a prototype is built to prove a single evaporator's feasibility that can simultaneously obtain freshwater and generate electricity. Thus, this membrane serves as an ocean wave power generation device that can provide all-weather energy generation, convert stored electrical energy into thermal energy at night and on cloudy days, and continuously provide safe drinking water.     

A 40 mW 3 Gb/s Self-Compensated Differential Transimpedance Amplifier With Enlarged Input Capacitance Tolerance in 0.18 $mu$m CMOS Technology

By combining an appropriate differential-sensing scheme with the bootstrapping technique, this paper presents a self-compensated design topology which is shown to be effective at reducing the loading effects due to the photodiode and the ESD protection circuit at the differential inputs. The built-in offset creation technique is introduced to overcome voltage headroom limitation. Furthermore, the negative impedance compensation is employed to enhance the gain-bandwidth product. The IC is shown to be tolerant of ESD protection circuit with 0.5 pF equivalent capacitance at the differential inputs. While connected to an InGaAs PIN photodiode exhibiting 0.8 pF equivalent capacitance, the implemented IC has achieved a differential transimpedance gain of 3.5 kOmega and a -3 dB bandwidth of 1.72 GHz. At a data rate of 3 Gb/s, the measured dynamic range is from -20 dBm to +0 dBm at a bit-error rate of 10^-12 with a 2³¹ -1 pseudorandom test pattern. The negative impedance compensation is shown to achieve enhancement factors of 4.5 dB and 520%, respectively, for transimpedance gain and - 3 dB bandwidth. The IC totally consumes 40 mW from a 1.8 V supply.     

Impact of Organic Contamination From Partially Fluorinated O-Ring in High-Temperature Nitride Process on DRAM Performance

This paper is concerned with organic contamination from a partially fluorinated o-ring used in a furnace for a high-temperature process. The organic outgas was confirmed by Fourier transform infrared analysis of the furnace exhaust gas. Experiments from practical trench dynamic random access memory disclosed that outgassed organic contaminants from the nitride process would severely worsen the tunneling leakage current performance of the storage dielectric and lead to fatal yield loss even though the cell capacitance was almost uninfluenced. To eliminate this yield detractor requires several test runs prior to real production after installation of the partially fluorinated o-ring; otherwise, a fully fluorinated o-ring is needed. From a cost viewpoint, the latter is highly suggested.