Achievable Sum Rate Optimization on NOMA-aided Cell-Free Massive MIMO with Finite Blocklength Coding

Non-orthogonal multiple access (NOMA)-aided cell-free massive multiple-input multiple-output (CFmMIMO) has been considered as a promising technology to fulfill strict quality of service requirements for ultra-reliable low-latency communications (URLLC). However, finite blocklength coding (FBC) in URLLC makes it challenging to achieve the optimal performance in the NOMA-aided CFmMIMO system. In this paper, we investigate the performance of the NOMA-aided CFmMIMO system with FBC in terms of achievable sum rate (ASR). Firstly, we derive a lower bound (LB) on the ergodic data rate. Then, we formulate an ASR maximization problem by jointly considering power allocation and user equipment (UE) clustering. To tackle such an intractable problem, we decompose it into two sub-problems, i.e., the power allocation problem and the UE clustering problem. A successive convex approximation (SCA) algorithm is proposed to solve the power allocation problem by transforming it into a series of geometric programming problems. Meanwhile, two algorithms based on graph theory are proposed to solve the UE clustering problem by identifying negative loops. Finally, alternative optimization is performed to find the maximum ASR of the NOMA-aided CFmMIMO system with FBC. The simulation results demonstrate that the proposed algorithms significantly outperform the benchmark algorithms in terms of ASR under various scenarios

Assimilation of GPS Refractivity from FORMOSAT-3/COSMIC Using a Nonlocal Operator with WRF 3DVAR and Its Impact on the Prediction of a Typhoon Event

A nonlocal observation operator has been developed to assimilate GPS radio occultation (RO) refractivity with WRF 3DVAR. For simplicity, in the past GPS RO refractivity was often assimilated using a local observation operator with the assumption that the GPS RO observation was representative of amodel local point. Such an operator did not take into account the effects of horizontal inhomogeneity on the derived GPS RO refractivity. In order to more accurately model the observables, Sokolovskiy et al. (2005a) developed a nonlocal observation operator, which would take into account the effects of horizontal inhomogeneity on GPS RO measurements. This nonlocal observation operator calculates the integrated amount of the model refractivity along the ray paths centered at the perigee points. For comparative purposes, the nonlocal observation operator can be simplified by limiting the length of integration near the RO point. This is called the "local operator variant", which is equivalent to the original local operator except that the original one is performed with fixed tangent points at observation levels. For computational efficiency, assimilation using both the nonlocal operator and local operator variant now is performed with smear tangent points at the mean height of each model vertical level. In this study, the statistics of observation errors using both local and nonlocal operators were estimated based on WRF simulations. The observation errors produced by the nonlocal operator are about two times smaller than those generated by the local operator and in agreement with Sokolovskiy et al. (2005b)

Investigative Study on Adaptive Thermal Comfort in Office Buildings with Evaporative Cooling Systems (ECS) under Dry Hot Climate

Evaporative cooling systems (ECS) in buildings, which are driven by cleaner and more sustainable energy, had been widely applied in recent years especially for the dry hot regions in summer. In this study, an investigation was conducted for office buildings by using ECS in Urumqi (China) from July to August 2021. Through subjective survey and objective measurements, 577 initial questionnaires and measured data were obtained. Outcomes showed that the indoor expectative temperature (Te) was received by 26.6 °C, 0.7 °C lower than neutral temperature (Tn). And the acceptable intervals for the 90% and 80% level were obtained at 27.1–28.9 °C and 26.4–30.3 °C, respectively. It appeared to possess a wider scope than that calculated by PMV algorithm, which further indicted that subjects have adapted to the local climate. Furthermore, the adjustment PMV models (ePMV, APMV) were found to have an effectively narrow gap comparing to the actual thermal sensation vote (TSV). The appropriate usage intervals of ePMV and APMV were quantified by Top < 27.6 °C/Top > 29.8 °C, 27.6 °C < Top < 29.8 °C, respectively. These findings may provide reference values for the revision of local energy-saving standard to some extent

Investigative Study on Adaptive Thermal Comfort in Office Buildings with Evaporative Cooling Systems (ECS) under Dry Hot Climate

Evaporative cooling systems (ECS) in buildings, which are driven by cleaner and more sustainable energy, had been widely applied in recent years especially for the dry hot regions in summer. In this study, an investigation was conducted for office buildings by using ECS in Urumqi (China) from July to August 2021. Through subjective survey and objective measurements, 577 initial questionnaires and measured data were obtained. Outcomes showed that the indoor expectative temperature (Te) was received by 26.6 °C, 0.7 °C lower than neutral temperature (Tn). And the acceptable intervals for the 90% and 80% level were obtained at 27.1–28.9 °C and 26.4–30.3 °C, respectively. It appeared to possess a wider scope than that calculated by PMV algorithm, which further indicted that subjects have adapted to the local climate. Furthermore, the adjustment PMV models (ePMV, APMV) were found to have an effectively narrow gap comparing to the actual thermal sensation vote (TSV). The appropriate usage intervals of ePMV and APMV were quantified by Top op > 29.8 °C, 27.6 °C op < 29.8 °C, respectively. These findings may provide reference values for the revision of local energy-saving standard to some extent

Adaptive Region Proposal Selection for SAR Target Detection Using Reinforcement Learning

Compared with optical images, the background clutter has a greater impact on feature extraction in Synthetic Aperture Radar (SAR) images. Due to the traditional redundant region proposals on the entire feature map, these algorithms generate large quantities of false alarms under the influence of clutter in SAR images, thereby lowering the target detection accuracy. To address this issue, this study proposes a Faster R-CNN model-based SAR target detection method, which uses reinforcement learning to realize adaptive region proposal selection. This method can adaptively locate areas that may contain targets on the feature map using the sequential decision-making characteristic of reinforcement learning and simultaneously adjust the scope of the next search area according to previous search results using distance constraints in reinforcement learning. Thus, this method can reduce the impact of complex background clutter and the computation of reinforcement learning. The experimental results based on the measured data indicate that the proposed method improves the detection performance

Une Architecture pour la Gestion de la Qualité de Service

Colloque avec actes et comité de lecture. internationale.International audienceDans cet article, nous proposons une architecture adaptative pour le contrôle et la gestion de la qualité de service pour des flux multimédias. l'accent est mis sur des stratégies d'adaptation qui permettent à l'application de réagir à des fluctuations de services du réseau en augmentant ou en diminuant le débit de la source. Nous introduisons le concept de réseaux multiples, où une machine client et une machine serveur sont reliées par plusieurs réseaux offrant une QdeS différente. L'architecture proposée est conforme au standard H.323 afin d'être compatible et interopérable avec d'autres applications suivant ces mêmes normes

Fast Finite-Time Super-Twisting Sliding Mode Control with an Extended State Higher-Order Sliding Mode Observer for UUV Trajectory Tracking

This paper proposes a trajectory tracking control scheme consisting of a fast finite-time super-twisting sliding mode control (FSTSMC) approach and an extended state higher-order sliding mode observer (ESHSMO) for unmanned underwater vehicles (UUVs) with external disturbances and model uncertainties. Firstly, an extended state higher-order sliding mode observer with the finite-time convergence is designed based on the higher-order sliding mode technique and the extended state observer technique. Next, on the basis of disturbances and model uncertainties observation, a fast finite-time super-twisting sliding mode control approach is proposed, and the finite time stabilization property of the tracking errors is proved by Lyapunov theory. Finally, through numerical simulation and experiment in a water pool, it has been verified that the proposed control scheme has achieved the high control precision, the smaller chattering, the disturbance compensation and the fast finite-time convergence in UUV trajectory tracking

Marking the status and development of marine VOCs recovery technology

During the storage and transportation of crude oil, volatile organic vapors (VOCs) are generated. International organizations and relevant countries have formulated relevant regulations for VOCs emissions. This article introduces four kinds of oil and gas recovery technologies and their combined processes: absorption method, adsorption method, membrane separation method and condensation method. The advantages and disadvantages of different oil and gas recovery technologies are analyzed and the process performance is compared. It lists examples of the application of oil and gas recovery technology in ships, points out its shortcomings, and puts forward relevant suggestions for the research of marine VOCs recovery technology

Dynamics of cadmium and arsenic at the capillary fringe of paddy soils: A microcosm study based on high-resolution porewater analysis

Arsenic (As) and cadmium (Cd) are prevalent in paddy soils, posing potential threats to food safety and public health. The concentrations of soluble ​As and Cd is sensitive to moisture-driven changes in soil pH and Eh, which is barely described at the critical dry-wet interface. Here, tempo-spatial changes of soluble As and Cd were captured by In-situ Porewater Iterative samplers at the capillary fringe that extended from saturated to unsaturated moisture gradient at the millimeter scale (60 ​mm profile in depth) through two episodic dry-wet cycles (55 days in total). The As and Cd concentrations showed less significant fluctuation in second cycle compared to the initial dry-wet cycle. The study also revealed at the capillary fringe profile (20–40 ​mm), the As concentrations increased from 4.6 μg L−1 in unsaturated soils to 13.5 μg L−1 in saturated soils, while Cd decreased from 3.3 to 0.2 μg L−1. This observed correlation was aligned with the vertical changes in soil Eh (+287 to +381 ​mV) and pH (3.42–6.07). This study found a distinct zone characterized by low As and low Cd concentrations, typically situated approximately 10–30 ​mm beneath the capillary fringe. Upon further analysis, it was determined that soil with an Eh of 249 ​mV and a pH of 4.3 potentially serves as an optimal environment for decreasing As and Cd levels in porewater. These findings suggest that it is feasible to reduce As and Cd concentration in the soil by implementing appropriate depth-controlled water management techniques

Observation of anti-dark solitons in fiber lasers

We report on the numerical simulation and experimental observation of anti-dark solitons in fiber lasers. The anti-dark solitons were obtained in the net normal near zero dispersion regions where the third-order dispersion plays a role. .Published versio