Simulation and experimental investigation of two hybrid solar domestic water heaters with drain water heat recovery

In this paper, the performance of two solar domestic hot waters (SDHW) with drain water heat recovery (DWHR) units is investigated. Both SDHW systems are recently installed at the Archetype Sustainable Twin Houses at Kortright Center, Vaughan, Ontario. The first SDWH system in House A consists of a flat plate solar thermal collector in combination with a gas boiler and a DWHR unit. The second SDHW system in House B includes an evacuated tube solar collector, an electric tank, and a DWHR unit. Both systems are modeled in TRNSYS, and the models are validated by experimental data. The addition of the DWHR and the flat‐plate solar thermal collector would result in 1831 kWh of annual energy saving in House A. While the addition of the DWHR and the evacuated tube collector in House B would result in an annual energy saving of 1771 kWh. Subsequently, the models are used to investigate the performance of similar systems for five major Canadian cities of Halifax, Montreal, Toronto, Edmonton, and Vancouver. The conjunctions of solar thermal collectors with DWHR units are found most beneficial in Edmonton. It is also noted from experimental and simulated results that flat‐plate solar collector‐based water heater produced more thermal energy than the system based on the evacuated tube solar collector for all major Canadian cities. Copyright © 2015 John Wiley & Sons, Ltd.     

Fast optical Layer mesh protection using pre-cross-connected trails

Conventional optical networks are based on SONET rings, but since rings are known to use bandwidth inefficiently, there has been much research into shared mesh protection, which promises significant bandwidth savings. Unfortunately, most shared mesh protection schemes cannot guarantee that failed traffic will be restored within the 50-ms timeframe that SONET standards specify. A notable exception is the p-cycle scheme of Grover and Stamatelakis. We argue, however, that p-cycles have certain limitations, e.g., there is no easy way to adapt p-cycles to a path-based protection scheme, and p-cycles seem more suited to static traffic than to dynamic traffic. In this paper we show that the key to fast restoration times is not a ring-like topology per se, but rather the ability to pre-cross-connect protection paths. This leads to the concept of a pre-cross-connected trail or PXT, which is a structure that is more flexible than rings and that adapts readily to both path-based and link-based schemes and to both static and dynamic traffic. The PXT protection scheme achieves fast restoration speeds, and our simulations, which have been carefully chosen using ideas from experimental design theory, show that the bandwidth efficiency of the PXT protection scheme is comparable to that of conventional shared mesh protection schemes.     

InP HBT integrated circuit technology with selectively implanted subcollector and regrown device layers

We describe a quasi-planar HBT process using a patterned implanted subcollector with a regrown MBE device layer. Using this process, we have demonstrated discrete SHBT with f/sub t/>250 GHz and DHBT with f/sub t/>230 GHz. The process eliminates the need to trade base resistance for extrinsic base/collector capacitance. Base/collector capacitance was reduced by a factor of 2 over the standard mesa device with a full overlap between the heavily doped base and subcollector regions. The low proportion of extrinsic base/collector capacitance enables further vertical scaling of the collector even in deep submicrometer emitters, thus allowing for higher current density operation. Demonstration ring oscillators fabricated with this process had excellent uniformity and yield with gate delay as low as 7 ps and power dissipation of 6 mW/CML gate. At lower bias current, the power delay product was as low as 20 fJ. To our knowledge, this is the first demonstration of high-performance HBTs and integrated circuits using a patterned implant on InP.     

RIE gate-recessed(Al0.3Ga0.7)0.5In0.5P/InGaAsdouble doped-channel FETs using CHF3+BCl3 mixingplasma

BCl₃+CHF₃ gas mixtures for the reactive ion etching process were applied to the gate-recess for fabricating (Al_0.3Ga_0.7)_0.5In_0.5P quaternary heterostructure double doped-channel FET's (D-DCFET), where a high uniformity of Vth was achieved. With the merits of this wide bandgap (Al_0.3Ga_0.7)_0.5In_0.5P layer, microwave power performance of this heterostructure D-DCFET demonstrates a compatible performance for devices fabricated on AlGaAs/InGaAs heterostructures     

A cascade energy band structure enhances the carrier energy in organic vertical-type triodes

Organic vertical-type triodes (OVTs) based on the cascade energy band structure as emitter layer are studied. The electric characteristics were dramatically enhanced while incorporating the cascade energy under current driving and voltage driving modes. The improvement is attributed to that injection carriers can obtain higher energy through a stepwise energy level. When the device has a layered structure of F₁₆CuPC (10 nm)/PTCDI (10 nm)/pentacene (100 nm) in emitter, it exhibits a common-base transport factor of 0.99 and a common-emitter current gain of 225 under current driving mode and exhibits a high current modulation-exceeding ?520 μA for a low collector voltage of ?5 V and a base voltage of ?5 V and the current on/off ratio of 10³ under voltage driving mode. Furthermore, we realized first organic current mirror that exhibited out/in current ratio of 0.75 and output resistance of 10⁵ Ω by using the OVTs.     

Coplanar waveguide with top and bottom shields in place ofair-bridges

A convenient technique for the elimination of the coupled slot-line mode in coplanar waveguide (CPW) nonsymmetric circuits is proposed. This technique simply uses top and/or bottom ground plane shields and avoids the more costly airbridges. These shields are easy to fabricate; however, they may slightly affect the propagation of the CPW mode in the form of power leakage into the parallel plate TEM mode. This effect can be avoided by restricting operation to lower frequencies. Numerical comparisons between the effect of the shields and the airbridges on a CPW filter are presented     

熔石英亚表面微缺陷原位表征及损伤阈值研究

通过对熔石英表面和亚表面划痕的原位测量,研究划痕的表面均方根(RMS)粗糙度、宽度和深度在HF溶液中刻蚀不同时间后的变化规律,测试了不同刻蚀时间下熔石英的损伤阈值。实验结果表明:随刻蚀时间的增加,表面RMS、划痕深度及宽度的总体变化趋势是增加的;熔石英的损伤阈值随刻蚀时间的增加,在1～10min时间段呈增加趋势,在20～40 min时间段呈下降趋势,而在60～120 min时间段先增加后降低。综合熔石英划痕的微观形貌损伤阈值的测量结果认为,刻蚀10 min时效果最佳。     

A Novel Character Segmentation Method for Text Images Captured by Cameras

Due to the rapid development of mobile devices equipped with cameras, instant translation of any text seen in any context is possible. Mobile devices can serve as a translation tool by recognizing the texts presented in the captured scenes. Images captured by cameras will embed more external or unwanted effects which need not to be considered in traditional optical character recognition (OCR). In this paper, we segment a text image captured by mobile devices into individual single characters to facilitate OCR kernel processing. Before proceeding with character segmentation, text detection and text line construction need to be performed in advance. A novel character segmentation method which integrates touched character filters is employed on text images captured by cameras. In addition, periphery features are extracted from the segmented images of touched characters and fed as inputs to support vector machines to calculate the confident values. In our experiment, the accuracy rate of the proposed character segmentation system is 94.90%, which demonstrates the effectiveness of the proposed method.     

A 1.8-V distributed voltage-controlled oscillator module for 5.8-GHz ISM band

This letter presents the design and implementation of a 1.8-V 5.8-GHz distributed voltage-controlled oscillator module based on bipolar transistors. The oscillator delivered -2-dBm-output power with a current consumption of 11.5 mA. The tuning range achieved was 650 MHz. The measured phase noise was -100 dBc/Hz at 1-MHz offset. The circuit construction was simple and robust and no buffer amplifier was needed. The design can be used for 5.8-GHz ISM band wireless LAN applications.     

The role of ion characteristics in determining the structural and electrical quality of InN grown by metalorganic molecular beam epitaxy

The effects of growth temperature and nitrogen plasma biasing on the electrical and structural properties of InN grown using electron cyclotron resonance metalorganic molecular beam epitaxy (ECR MOMBE) have been investigated. These results are compared to those found from InN grown using a higher energy radio frequency (rf) plasma source (rf MOMBE). By varying the bias of the nitrogen plasma or the growth temperature, it is possible to achieve smooth surface morphologies. However, biasing can also be used to increase the mobility by a factor of two while the growth temperature has only a small effect. By contrast, use of an rf plasma improves mobility by nearly a factor of ten. None of the growth conditions investigated were found to significantly alter the electron concentration, which was measured to be 1−5 × 10²⁰ cm⁻³.