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Aiming at the problem of waveform distortion and false components in the Intrinsic Time-scale Decomposition (ITD)algorithm, an Modified Intrinsic Time-scale Decomposition (MITD) algorithm is proposed. Compared with the traditional ITD, the MITD algorithm can not only smooth the signal, but also retain the characteristic data effectively. In order to solve the problem of fault detection in photovoltaic (PV) microgrids, a multi-feature fusion fault detection scheme combined with MITD-DNN is designed. Firstly, the three-phase voltage amplitude of the branch is collected, the modified ITD is used to decompose the collected data and extract the characteristic values, after feature selection, the fused feature matrix was trained in deep neural network (DNN), and fault types and fault phases were accurately identified according to the classification results of deep neural network. In order to evaluate the performance of the proposed fault detection scheme, a microgrid based on IEC-61850 standard is comprehensively evaluated and studied, and the test results prove the effectiveness of the scheme.

The fabrication of nanoporous (NP) GaN is proposed as a generic technique to create out-of-plane index guiding for nitride microcavities. Compared to the conventional undercut technique, the proposed technique forms uniformly a low-index NP-GaN layer beneath the entire microcavity. Therefore, it supports all cavity modes (with different cavity geometries), while the undercut technique only supports the modes that reside at the circumference of a circular microcavity. As a proof of concept, GaN microdisk cavities were fabricated with the NP-GaN as the bottom low-index medium. A cold cavity with Q>2,000 was reported under continuous-wave pumping. Lasing was demonstrated with threshold optical pumping power Pth∼60 kW/cm2 for the r=10 μm microdisk and Pth∼7 kW/cm2 for the r=50 μm microdisk. A rate equation analysis was performed to estimate the spontaneous coupling factor β∼1E-3, which was one order of magnitude higher than the previous report of a nitride microdisk laser with an InGaN quantum well active region. Therefore, NP GaN was proven to be a suitable replacement of the undercut technique for future nitride microcavities applications.

By using a novel conductivity-based selective electrochemical etching, we have introduced nanometer-sized pores into GaN to significantly decrease its refractive index while maintaining its crystallinity. Such advantages of nanoporous (NP) GaN can thus overcome the epitaxial (strain) and optical (index) limitations of AlGaN, which has been used as the cladding layers in InGaN laser diodes for two decades. Compared to Al0.1Ga0.9GaN cladding, which has a refractive index contrast (Δn) of 0.04 to GaN, the Δn of NP-GaN to GaN can be engineered to be over 0.4 without inducing any tensile strain. The high Δn not only increases the optical confinement factor (Γ) from lower than 3% in the state-of-the-art (SOTA) InGaN laser diodes to 9% but also offers a broad tunability of the Γ and the modal gain as well. We have observed a clear correlation between the Γ and the modal gain by using the variable stripe length method and have demonstrated an over 100% increase of the modal gain by engineering the Γ of the wavegu...

We have developed a novel conductivity based selective electrochemical etching to introduce nanometer sized pores into GaN. The nanoporous (NP) GaN can be considered as a new form of GaN with an unprecedented tunability in optical index. The advantages of NP-GaN for both edge-emitting laser diodes and vertical surface-emitting laser diodes (VCSEL) are subsequently exhibited.

Here, we analyze the chemical vapor deposition of semiconductor crystals by selective area growth in a non-planar geometry. Specifically, the growth process in laterally and vertically confined masks forming single-crystal GaN on SiO 2 by metal-organic chemical vapor deposition is considered in detail. A textured AlN seed is used to initiate growth of oriented GaN selectively through the mask, allowing the reduction of degrees of freedom by the evolutionary grain selection process. As shown by measurements of growth rates within the mask, the sub micron length scale of the channel opening is comparable to the mean free path of precursors in the gas phase, resulting in transport characteristics that can be described by an intermediate flow regime between continuum and free-molecular. Mass transport is modeled through kinetic theory to explain the growth rate enhancements of more than a factor of two by changes in reactor pressure. The growth conditions that enable the modification of nucleation density within the channel are then discussed, and are measured by electron-back scatter diffraction of the nucleated grains on the AlN seed. Finally, the selectivity behavior using the low fill factor masks needed in these configurations has been optimized by control of precursor flow rates and the H 2 enhanced etching of the polycrystalline GaN nuclei.

Bacterial communities in fermentative high-temperature Daqu play an important role in the Chinese roasted sesame-like flavour liquor brewing process. A culture-independent method of 16S rDNA clone library was applied to investigate the changes in bacterial diversity during the process of a Daqu fermentation. The results indicated that the types of bacteria species gradually increased with prolonged fermentation time. The first dominant bacterium, Pantoea sp. (73.68%), in the raw material was only detected at the beginning of the fermentation stage (8 days) in small quantities. The second dominant bacterium, Weissella sp. (16.99%) and the third, Lactobacillus sp. (4.57%), were both detected in the beginning fermentation sample (3.22, 11.29%), in the ripening fermentation sample (24 days; 6.89, 25.11%) and in the drying stage (49 days; 3.74, 7.47%). In the beginning fermentation, Thermoactinomyces sp. (47.57%) was detected as the first predominant bacterium, and it was also detected in the ripening fermentation stage (4.93%) and in the drying stage (15.68%). The bacterial communities in the Daqu fermentation process affected the physicochemical index of Daqu. A molecular analysis of the bacterial community from the Daqu fermentation process will benefit studies on the aroma production mechanisms from these bacteria. Copyright © 2015 The Institute of Brewing & Distilling

A new photo alignment (PA) polyimide for in-plane switching (IPS) liquid crystal display has been presented and it has good alignment performance. It realizes alignment by irradiating linearly polarized light with wavelength of 313nm. In this paper, we have study a novel 313nm PA polyimide with only one UV step. And we also have investigated the relationship between the image sticking performance and PA polyimide structure. The optical and image sticking performance of different PA polyimide are discussed in IPS mode, respectively.

In this work, we have successfully fabricated microtubes by strain-induced self-rolling of a InGaN/GaN quantum wells nanomembrane. Freestanding quantum wells microtubes, with a diameter of 6 µm and wall thickness of 50 nm, are formed when the coherently strained InGaN/GaN quantum wells heterostructure is selectively released from the hosting substrate. Periodic oscillations due to whispering-gallery modes resonance were found superimposed on photoluminescence spectra even at low optical excitation power. With increasing pumping power density, the microtube is characterized by a stimulated emission with a threshold as low as 415 kW/cm2. Such emission shows predominant TM polarization parallel to the microtube axis.

Single crystal semiconductor nanomembranes (NM) are important in various applications such as heterogeneous integration and flexible devices. This paper reports the fabrication of AlGaN/GaN NMs and NM high electron mobility transistors (HEMT). Electrochemical etching is used to slice off single-crystalline AlGaN/GaN layers while preserving their microstructural quality. A double heterostructure design with a symmetric strain profile is employed to ensure minimal residual strain in freestanding NMs after release. The mobility of the two-dimensional electron gas (2DEG), formed by the AlGaN/GaN heterostructure, is noticeably superior to previously reported values of many other NMs. AlGaN/GaN nanomembrane HEMTs are fabricated on SiO2 and flexible polymeric substrates. Excellent electrical characteristics, including a high ON/OFF ratio and transconductance, suggest that III-Nitrides nanomembranes are capable of supporting high performance applications.

This paper presents an engineering investigation on the impact of well trajectory on production performance of ESP-lifted shale wells. A representative set of field data was selected as the input data to model the shale well with an ESP installed. Based on these data, a comprehensive analysis of production performance from ESP-lifted shale wells was performed. These wells had the same or similar reservoir characteristics, but different well trajectories including relatively smooth and highly sinuous toe-up and toe-down well trajectories. A transient dynamic multiphase simulator was used to perform the engineering investigation by integrating ESP performance and wellbore models over the life of a shale well, evolving from initial steady natural flow production to late-life unsteady and slugging flow production. From the analysis, the well trajectory does not impact the well production performance of an ESP-lifted well. The slugging flow results in a dramatic gas volume fraction changing from 0 to up to 100% at the pump intake. The study combines multiphase transient modeling (for the specific well trajectory) with reservoir modeling and historic production data. The analysis includes models of the well behavior and instabilities that allow operators to evaluate the application of ESP systems considering well trajectory and optimize timing for installation and withdrawal.

Large-area, free-standing and single-crystalline GaN nanomembranes are prepared by electrochemical etching from epitaxial layers. As-prepared nanomembranes are highly resistive but can become electronically active upon optical excitation, with an excellent electron mobility. The interaction of excited carriers with surface states is investigated by intensity-dependent photoconductivity gain and temperature-dependent photocurrent decay. Normally off enhancement-type GaN nanomembrane MOS transistors are demonstrated, suggesting that GaN could be used in flexible electronics for high power and high frequency applications.

Based on the analyses of the recent routing research productions of the cognitive radio networks, this paper identifies five critical challenges on the routing research of CRN: neighbor discovery, deafness problem, neighbor disappearance, routing problem and cross2layer design, then some topics about common control channel ,path delay and the technical metrics are discussed from the view of research method, which must be considered on the routing research of CRN. After that,we summarize and analyze the scenario design patterns of routing research from four aspects: medium, channel, node and network; study and discuss the main research productions from the views of optimization scheme and routing topology algorithm/ protocol in detail at the end of this paper.

Recently, nanoporous (NP) GaN has emerged as a promising photonic material in the III-N family. Due to its attractive properties, such as its large refractive index contrast and perfect lattice matching with GaN, as well as its good electrical conductivity, photonic components and devices involving NP GaN have been successfully demonstrated. However, further development of high-performance NP GaN based electrically injected devices, such as vertical-cavity surface-emitting lasers (VCSELs) and edge emitting lasers, requires efficient heat dissipation. Therefore, in this paper, we study thermal conductivity (TC) of NP GaN, especially when incorporated into a practical distributed Bragg reflector (DBR) in a VCSEL device. Through an effective medium model, we study the theoretical effect of NP GaN morphological properties over its TC. We then experimentally measure the TC of NP GaN, with different porosities and pore wall thicknesses, which shows a high agreement with the theoretical model. We also fabricate actual NP GaN DBRs and study the large tunability and interdependence among their TC (1–24 W/m K), refractive index (0.1–1.0), and electrical conductivity (100–2000 S/m) compared to other conventional DBRs. Finally, we perform a finite-element simulation of the heat dissipation within NP GaN-VCSELs, revealing their superior thermal dissipation compared to dielectric DBR based VCSELs. In this regard, this study lays the foundation for nanoscale thermal engineering of NP GaN optoelectronic and photonic devices and paves the way for their successful commercialization.

Nanoporous (NP) gallium nitride (GaN) as a new class of GaN material has many interesting properties that the conventional GaN material does not have. In this paper, we focus on the mechanical properties of NP GaN, and the detailed physical mechanism of porous GaN in the application of liftoff. A decrease in elastic modulus and hardness was identified in NP GaN compared to the conventional GaN film. The promising application of NP GaN as release layers in the mechanical liftoff of GaN thin films and devices was systematically studied. A phase diagram was generated to correlate the initial NP GaN profiles with the as-overgrown morphologies of the NP structures. The fracture toughness of the NP GaN release layer was studied in terms of the voided-space-ratio. It is shown that the transformed morphologies and fracture toughness of the NP GaN layer after overgrowth strongly depends on the initial porosity of NP GaN templates. The mechanical separation and transfer of a GaN film over a 2 in. wafer was demonstrated, which proves that this technique is useful in practical applications.

We have developed a novel conductivity based selective electrochemical etching to introduce nanometer sized pores into GaN. By controlling the doping and electrochemical etching bias, we are able to control the pore morphology. The nanoporous (NP) GaN can be considered a new form of GaN with an unprecedented tunability in optical index We show the potential of this NPGaN to overcome the optical and epitaxial limitations of AlGaN, which has been the bottleneck for GaN-based laser diodes for decades. The advantages of NP-GaN for both vertical surfaceemitting laser diodes (VCSEL) and edge-emitting laser diodes are exhibited in subsequent sections. We first demonstrate the record high reflectances (R > 99.5 %) from epitaxial NP-GaN mirrors, which are used in a low threshold optically pumped VCSEL. We then show a two-fold increase of modal gain in an edge-emitting waveguide geometry with optical confinement Γ engineering. The increase of the Γ also leads to a two-fold reduction in the threshold power density under optical pumping with a threshold material gain of 400 cm-1, which is more than two times lower than previously reported (> 1,000 cm-1).

The gain characteristics of Er x Y 2 − x SiO 5 waveguide amplifiers have been investigated by solving rate equations and propagation equations. The gain at 1.53 μm as a function of waveguide length, Er 3+ concentration and pump power is studied pumping at three different wavelengths of 654 nm, 980 nm and 1480 nm, respectively. The optimum Er 3+ concentrations of 1 × 10 21 cm − 3 –2 × 10 21 cm − 3 with the high gain are obtained for all three pump wavelengths. Pumping at 654 nm wavelength is shown to be the most efficient one due to weak cooperative upconversion. A maximum 16 dB gain at 1 mm waveguide length under a 30 mW pump with Er 3+ concentration of 1 × 10 21 cm − 3 is demonstrated pumping at 654 nm wavelength.

While III-Nitride micro-cavity light emitters are of great interest, electrically conductive and optically highly reflective distributed Bragg mirrors remain a major challenge. In this paper, we demonstrate a blue–violet resonant-cavity light-emitting diode (RC-LED) with a novel conductive nanoporous (NP)-GaN/GaN DBR as the bottom mirror. The NP-DBR is converted from an all-GaN epitaxial structure with modulated doping profile, and formed by using a conductivity-selective anodic electro-chemical etching process. The NP-GaN material has a tunable index of refraction and maintains its electrical conductivity. The benefits of such NP-DBR RC-LED include a more efficient quasi-vertical current injection scheme benefited from the conductive NP-DBR, and a manufacturable fabrication process, which makes NP-DBR a unique opportunity for the commercialization of GaN-based vertical-cavity surface emitters.

A gas entrained flow experimental device of making water gas using microwave as a secondary heat source was established, and absorbing agent was used as the heat transfer medium. Under optimum conditions, the microwave energy consumption per unit mass of coal gasification was only 75.2 kJ · kg −1, and the volume fraction of CO and H 2 in the water gas was 94.4%. The stable gasification temperatures or water gas compositions had nothing to do with the amounts of the coal for gasification. With the mass ratios of the coal to absorbing agent decreasing, the gasification temperatures were increased; the contents of CO 2, H 2 and CH 4 in the product water gas were reduced evenly, also, the content of CO was increased; the change in the amplitude of variation was anthracite < bituminous coal < lignite. The reaction rate can be greatly improved by using multi-branched parallel reactors instead of one single larger diameter reactor. [Received: August 22, 2015; Accepted: March 13, 2016]

Single crystalline nanomembranes (NMs) represent a new embodiment of semiconductors having a two-dimensional flexural character with comparable crystalline perfection and optoelectronic efficacy. In this Letter, we demonstrate the preparation of GaN NMs with a freestanding thickness between 90 to 300 nm. Large-area (5 × 5 mm(2)) GaN NMs can be routinely obtained using a procedure of conductivity-selective electrochemical etching. GaN NM is atomically flat and possesses an optical quality similar to that from bulk GaN. A light-emitting optical heterostructure NM consisting of p-GaN/InGaN quantum wells/GaN is prepared by epitaxy, undercutting etching, and layer transfer. Bright blue light emission from this heterostructure validates the concept of NM-based optoelectronics and points to potentials in flexible applications and heterogeneous integration.

As the GaN material research is reaching maturity with the phenomenal success in LED industry, there is now need to look beyond conventional epitaxy. In this paper we will summarize a few novel directions that we are pursuing. In the first part of this paper, we highlighted our effort to grow single crystal GaN on amorphous substrate. With the successive applications of a phenomenon called evolutionary selection along two perpendicular axes, we remove the degree of freedom in grain orientations from 3 to 0 and successfully prepared single-crystalline GaN on amorphous oxide template. We dedicated the second part of this paper to our recent findings in GaN nanomembrane. Via conductivity selective electrochemical etching, we have fabricated GaN nanomembrane as thin as 90 nm. The thin and “soft” GaN nanomembrane is proven to maintain its as-grown crystal quality. We have also demonstrated a 300 nm thick InGaN/GaN nanomembrane LED.

In networked control systems (NCSs), the presence of communication networks in control loops causes many imperfections such as random delays, packet losses, multipacket transmission, and packet disordering. In fact, random delays are usually the most important problems and challenges in NCSs because, to some extent, other problems are often caused by random delays. In order to compensate for random delays which may lead to performance degradation and instability of NCSs, it is necessary to establish the mathematical model of random delays before compensation. In this paper, four major delay models are surveyed including constant delay model, mutually independent stochastic delay model, Markov chain model, and hidden Markov model. In each delay model, some promising compensation methods of delays are also addressed.

To achieve a strong forward-looking control function, and to reduce the memory occupation, the paper puts forward that the buffer method should be adopted for the information exchange between the interpreter module and the motion module of the computerized numerical controller (CNC). The paper also puts forward that the linear chain structure of the CNC program buffer should be improved into the circular buffer structure to reduce the command dispatch spending for the task module. The paper has established the information exchange model between real-time modules and non-real-time modules with the shared memory. The capability of CNC system has been verified by the experiments. The test result shows that the speed of the CNC interpreter and the speed planning performance of the motion module have been improved. The efficiency of the machine tool equipped with the CNC system has been improved 5% more than before. In summary, the paper draws the conclusion that the CNC system developed with the static data structure of the circular buffer and with pointer operation to avoid the data replication contributes to improving the real-time capability of the system.

The photoluminescence (PL) and decay time at 1.53μm of sputtered Er 0.2 Re 1.8 Si 2 O 7 (Re=Yb, Y) thin films were investigated. The enhancement of the PL at 974nm pumping in the Er 0.2 Re 1.8 Si 2 O 7 film was demonstrated compared with Er 0.2 Re 1.8 Si 2 O 7 film.

This study was designed to compare the approaches and efficacies of two different ways of neurosurgical management for spontaneous putaminal hemorrhage (SPH): computed tomographic-guided aspiration (CTGA) and the key-hole approach (KHA). The indications of the two approaches are also explored. From September 2001 to 2003, a total of 1077 cases of SPH distributed in 135 hospitals all over the mainland of China were included for analysis. All cases had three-month follow-up data. The study was designed in a single-blinded manner to compare the efficacies of the different approaches. There were 563 cases in the CTGA group, 165 in the KHA group, and 217 cases in the conventional open craniotomy (COC) group. In the CTGA and KHA groups, the mortalities at one month after operation (M1m) were 17.9% and 18.3%, respectively, while the mortalities at three months after operation (M3m) were 19.4% and 19.4%, respectively (P0.05). The postoperative complications due to CTGA (23.7%) were not significantly different from those due to KHA (25.7%) (P = 0.420). The M3m of patients with Glasgow coma scale (GCS) [Symbol: see text]8 was 3.45 and 4.0 times as much as those with GCS8, respectively. The M3m of patients with complications was 3.92 times as much as those without complications. The M3m of patients with hemorrhage volume [Symbol: see text]70 mL was 2.67 times as much as those70 mL. The CTGA is not better than KHA in the treatment of SPH in terms of a more favorable outcome or less mortality and morbidity, but CTGA could be the first choice for those with bleeding volumes ≤50mL, while KHA is the first choice for those with bleeding volumes50 mL.

Conventional epitaxial techniques requires single crystalline substrates to form semiconductor material of desired material quality for device applications. The use of amorphous substrates, in many applications, provides an opportunity to consider new materials and designs, which can fundamentally alter the performance, functionality and/or cost limitations of many optoelectronic devices. Here, a growth process is described to achieve single crystalline GaN material on amorphous SiO2. The evolutionary selection principle in crystal growth is the basis of this technique, and the mechanism is described and analyzed in detail. It is expected that this process can be extended to other semiconductor and substrate combinations, allowing heterogenous integration with functional substrates to produce new classes of semiconductor devices.