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Currently, Quality-of-Service (QoS)-aware routing is one of the crucial challenges in Software Defined Network (SDN). The QoS performances, e.g. latency, packet loss ratio and throughput, must be optimized to improve the performance of network. Traditional static routing algorithms based on Open Shortest Path First (OSPF) could not adapt to traffic fluctuation, which may cause severe network congestion and service degradation. Central intelligence of SDN controller and recent breakthroughs of Deep Reinforcement Learning (DRL) pose a promising solution to tackle this challenge. Thus, we propose an on-policy DRL mechanism, namely the PPO-based (Proximal Policy Optimization) QoS-aware Routing Optimization Mechanism (PQROM), to achieve a general and re-customizable routing optimization. PQROM can dynamically update the routing calculation by adjusting the reward function according to different optimization objectives, and it is independent of any specific network pattern. Additionally, as a black-box one-step optimization, PQROM is qualified for both continuous and discrete action space with high-dimensional input and output. The OMNeT ++ simulation experiment results show that PQROM not only has good convergence, but also has better stability compared with OSPF, less training time and simpler hyper-parameters adjustment than Deep Deterministic Policy Gradient (DDPG) and less hardware consumption than Asynchronous Advantage Actor-Critic (A3C). [ABSTRACT FROM AUTHOR]

The link between anthropogenic emissions of carbon dioxide, increasing atmospheric C[O.sub.2] levels, and concomitantly increasing global temperatures is established and accepted. The use of aqueous ammonia, to capture C[O.sub.2] and produce an inexpensive nitrogen fertilizer, ammonium bicarbonate (ABC), is believed to be a feasible approach to C[O.sub.2] sequestration. Due to the varying concentrations of reactants and varying reaction conditions, different ammonia--carbon compounds may be produced. ABC is the ideal product for maximizing N[H.sub.3] utilization in C[O.sub.2] capture; therefore, identification and quantification of ABC in the reaction products is mandatory. Various analytical techniques were used to distinguish and quantify the ABC. Fourier transform infrared spectroscopy can only be used to distinguish ammonium carbamate, and. X-ray diffraction can be used to qualitatively distinguish ABC from the other possible products of the C[O.sub.2] capture reaction. Carbon--hydrogen--nitrogen elemental analysis and near-infrared (NIR) spectroscopy were used to quantify ABC, with both techniques giving [+ or -] 5% agreement for ABC concentrations for 8 of 13 samples from a bench-scale aqueous ammonia C[O.sub.2] scrubbing system. An additional 3 of the 13 samples were within [+ or -] 12%. Results indicate that NIR will be an ideal tool for real-time, online measurements of ABC in a full-scale aqueous ammonia C[O.sub.2] scrubber. The ABC in 11 samples from the bench-scale scrubber at Western Kentucky University was determined by these techniques and assessed to have very good quality as a fertilizer in accordance with GB-3559-92, the Agricultural Ammonium Bicarbonate National Standard of China.

High crystalline quality thick β-Ga2O3 drift layers are essential for multi-kV vertical power devices. Low-pressure chemical vapor deposition (LPCVD) is suitable for achieving high growth rates. This paper presents a systematic study of the Schottky barrier diodes fabricated on four different Si-doped homoepitaxial β-Ga2O3 thin films grown on Sn-doped (010) and (001) β-Ga2O3 substrates by LPCVD with a fast growth rate varying from 13 to 21 μm/h. A higher temperature growth results in the highest reported growth rate to date. Room temperature current density–voltage data for different Schottky diodes are presented, and diode characteristics, such as ideality factor, barrier height, specific on-resistance, and breakdown voltage are studied. Temperature dependence (25–250 °C) of the ideality factor, barrier height, and specific on-resistance is also analyzed from the J–V–T characteristics of the fabricated Schottky diodes. [ABSTRACT FROM AUTHOR]

The β-(AlxGa1−x)2O3 alloy represents an emerging ultrawide bandgap semiconductor material for applications in high-power electronics and deep ultraviolet optoelectronics. The recent demonstrations of orientation-dependent epitaxial growth of high quality β-(AlxGa1−x)2O3 films have unlocked prospects for the development of ultrahigh frequency β-(AlxGa1−x)2O3/Ga2O3 based transistors with high-power tolerance. To control the electronic and optical properties of β-(AlxGa1−x)2O3/Ga2O3 heterostructure-based devices, an understanding of the band offsets between β-(AlxGa1−x)2O3 and β-Ga2O3 is crucial. However, there have been no systematic experimental studies on the evolution of the band offsets between differently oriented β-(AlxGa1−x)2O3/Ga2O3 heterointerfaces as a function of Al compositions. This work presents the valence and conduction band offsets at (010) and (2 ¯ 01) oriented β-(AlxGa1−x)2O3/Ga2O3 interfaces using x-ray photoelectron spectroscopy. β-(AlxGa1−x)2O3 films with x ≤ 0.35 and x ≤ 0.48 were grown by metalorganic chemical vapor deposition on (010) and (2 ¯ 01) oriented β-Ga2O3 substrates, respectively. The determined band offsets reveal the formation of a type-II (staggered) band alignment at (010) oriented β-(AlxGa1−x)2O3/Ga2O3 and a type-I (straddling) heterojunction between (2 ¯ 01) β-(AlxGa1−x)2O3 and β-Ga2O3. For both crystalline orientations, the valence and conduction band offsets are found to increase with increasing Al content with a much weaker variation in the valence band offsets as compared to the conduction band offsets. Among different orientations investigated, such as (010), (2 ¯ 01) , and (100), the largest conduction band offset occurs at a β-(AlxGa1−x)2O3/Ga2O3 interface with (100) orientation, providing opportunities for excellent electron confinement with a high-density two-dimensional electron gas. Results from this study on the tunable and orientation-dependent band offsets with the variation of the Al alloy fraction will provide guidance for the design of heterostructures in future β-(AlxGa1−x)2O3/Ga2O3 based devices. [ABSTRACT FROM AUTHOR]

Owing to the merits of high cost-effectiveness and satisfying eco-efficiency, rechargeable zinc ion batteries (ZIBs) are feasible electrical energy storage systems for improving grid reliability. However, viable cathode materials usually suffer from sluggish kinetics and limited stability. Herein, this article reports a facile recrystallization/reduction strategy to make anion-deficient Na2V6O16 nanobelt (denoted as ANVO), in which the coexistence of nanostructure and oxygen vacancy facilitates Zn2+ reaction kinetics for a superior high specific capacity of 458 mA h g−1 at 500 mA g−1. DFT calculation demonstrates that the oxygen vacancy can strengthen V–O bonds and narrow the band gap to improve the electrical conductivity. The in-depth analysis of the storage mechanism is also revealed by in situ XRD. The ultra-thin Na2V6O16 nanobelts (∼10 nm thickness) harvest prominent long-term reliability and gain favorable zinc storage ability even at a large current density of 10 000 mA g−1 after 5000 cycles, suggesting its great potential for ZIBs. This work not only provides fresh insight into the design of deficiency-modified sodium vanadate cathodes but also broadens the scope for understanding its electrochemical properties and energy-storage mechanism in rechargeable zinc-ion batteries. [ABSTRACT FROM AUTHOR]

Single α-phase (AlxGa1−x)2O3 thin films are grown on m-plane sapphire (α-Al2O3) substrates via metalorganic chemical vapor deposition. By systematically tuning the growth parameters including the precursor molar flow rates, chamber pressure, and growth temperature, the epitaxial growth of high-quality phase pure α-(AlxGa1−x)2O3 films (0 ≤ x ≤ 1) is demonstrated with smooth surface morphologies and alloy homogeneities by comprehensive material characterization. The asymmetrical reciprocal space mapping reveals fully relaxed films for α-(AlxGa1−x)2O3 films with x ≤ 0.5. The coherent growth of α-(AlxGa1−x)2O3/α-Al2O3 superlattice structures is demonstrated with abrupt interfaces and uniform Al distribution for higher Al compositions at x = 0.78 in the α-(AlxGa1−x)2O3 layer. The influence of growth parameters, such as growth temperature and chamber pressure, on the phase stabilization and Al incorporation in the α-(AlxGa1−x)2O3 films is investigated. While lower growth temperatures facilitate the phase stabilization of α-Ga2O3 thin films, lower chamber pressure leads to higher Al incorporation in α-(AlxGa1−x)2O3 films. High resolution x-ray photoelectron spectroscopy was utilized for determining the Al compositions and bandgaps of α-(AlxGa1−x)2O3. Furthermore, the evolution of the valance and conduction band offsets at α-Al2O3/α-(AlxGa1−x)2O3 heterojunctions is evaluated with the variation of Al compositions, which reveals the formation of type-I (straddling) band alignment between α-Al2O3 and α-(AlxGa1−x)2O3. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrated large-size free-standing single-crystal β-Ga2O3 NMs fabricated by the hydrogen implantation and lift-off process directly from MOCVD grown β-Ga2O3 epifilms on native substrates. The optimum implantation conditions were simulated with a Monte-Carlo simulation method to obtain a high hydrogen concentration with a narrow ion distribution at the desired depth. Two as grown β-Ga2O3 samples with different orientations ([100] and [001]) were used to successfully create 1.2 μm thick β-Ga2O3 NMs without any physical damage. These β-Ga2O3 NMs were then transfer-printed onto rigid and flexible substrates such as SiC and polyimide substrates. Various material characterization studies were performed to investigate their crystal quality, surface morphologies, optical properties, mechanical properties, and bandgaps before and after the lift-off and revealed that the good material quality was maintained. This result offers several benefits in that the thickness, doping, and size of β-Ga2O3 NMs can be fully controlled. Moreover, more advanced β-Ga2O3-based NM structures such as (AlxGa1−x)2O3/Ga2O3 heterostructure NMs can be directly created from their bulk epitaxy substrates; thus this study provides a viable route for the realization of high performance β-Ga2O3 NM-based electronics and optoelectronics that can be built on various substrates and platforms. [ABSTRACT FROM AUTHOR]

Summary: Modern smartphone platforms offer a multitude of useful features to their users, but at the same time, they highly affect privacy, which may lead to unnecessary personal data being collected. In this paper, we proposed an evolutionary game model to study permission request strategies of the bounded rational application providers. We study the proposed model with detailed simulations. Initial results demonstrate that evolution processes are influenced by four factors: revenue increase ratio, market share, credit cost, and market attraction. It also suggests that establishing a privacy alarm mechanism not only can improve the users' privacy awareness but also decrease the market share when providers over‐request permissions and push them request permissions properly. [ABSTRACT FROM AUTHOR]

β-phase gallium oxide (Ga2O3) is an emerging ultrawide bandgap (UWBG) semiconductor with a bandgap energy of ∼ 4.8 eV and a predicted high critical electric field strength of ∼8 MV/cm, enabling promising applications in next generation high power electronics and deep ultraviolet optoelectronics. The advantages of Ga2O3 also stem from its availability of single crystal bulk native substrates synthesized from melt, and its well-controllable n-type doping from both bulk growth and thin film epitaxy. Among several thin film growth methods, metalorganic chemical vapor deposition (MOCVD) has been demonstrated as an enabling technology for developing high-quality epitaxy of Ga2O3 thin films, (AlxGa1−x)2O3 alloys, and heterostructures along various crystal orientations and with different phases. This tutorial summarizes the recent progresses in the epitaxial growth of β-Ga2O3 thin films via different growth methods, with a focus on the growth of Ga2O3 and its compositional alloys by MOCVD. The challenges for the epitaxial development of β-Ga2O3 are discussed, along with the opportunities of future works to enhance the state-of-the-art device performance based on this emerging UWBG semiconductor material system. [ABSTRACT FROM AUTHOR]

Summary: A major concern of the deployment of location based services (LBSs) is the safeguards of the user's location data collected by service providers, since personal location data may imply sensitive private information. However, most available works proposed so far rely on syntactic privacy models such as k‐anonymity and location perturbation, which are proved to quiver in the balance with privacy and usability requirements. In this article, we provide a new γ‐map mechanism to help users better understand the privacy/accuracy tradeoff process and preserve location data. In our γ‐map model, the user can specify a geographic region to hide her precise location and suppress the following queries in the same area to meet her privacy requirement, while maintaining and understanding its usability. In addition, we propose a new notion of εΔt‐privacy based on differential privacy to account for the temporal‐spatial correlation and history correlation in the case of crossing region, which is the major privacy concern of a moving user's trace. Finally, we evaluate our framework by using an online LBS with real‐world data sets. The results not only indicate that the γ‐map is significantly useful for identifying the privacy and utility tradeoffs but also show the effectiveness and practicality of the proposed εΔt‐privacy. [ABSTRACT FROM AUTHOR]

Background: Endoscopic sphincterotomy (EST) can destroy sphincter of Oddi (SO) structure and function. The purpose of this study was to assess the feasibility of endoscopic endoclip papilloplasty (EEPP) in restoring SO function after EST. Methods: Seven 26‐week‐old domestic pigs were divided into control and EEPP groups. Necropsy and haematoxylin‐eosin staining plus anti‐α‐smooth muscle actin (α‐SMA) staining of papilla and sphincter of Oddi manometry (SOM) were conducted in animals at three independent time points. Results: EST and EEPP were safely performed in all 7 pigs without serious adverse events. For primary outcome, compared to the controls, EEPP generated smaller dilation and less inflammation. Fibrous repair of the papilla was observed at 24 weeks after EEPP. For secondary outcome, in the control group, SO basal pressure (17.25 ± 18.14 to 5.50 ± 0.71 mmHg), SO contraction amplitude (46.00 ± 19.20 to 34.50 ± 48.79 mmHg), peak (4.50 ± 4.04 to 1.50 ± 2.12) and frequency (3.05 ± 3.29 to 1.41 ± 2.19/min) were reduced after EST. Further reductions to almost 0 of these SOM parameters were observed 3 weeks later, including common bile duct pressure and SO contraction period. In contrast, in the EEPP group, these manometric data were recovered to pre‐EST levels, including CBD pressure (11.5 ± 7.31 vs 11 ± 2.16 mmHg), SO pressure (17.50 ± 17.75 vs 18.20 ± 21.39 mmHg) and SO contraction amplitude (53.67 ± 21.54 vs 60.00 ± 36.08 mmHg). However, no significant differences were observed between control and EEPP groups by Student t test. Conclusions: In this porcine study, EEPP accelerated and improved papillary healing after EST, further preserved SO function. [ABSTRACT FROM AUTHOR]