This article proposes a simple stopping criterion for turbo decoding that extends the existing sign change ratio (SCR) technique. The new difference (SDR) counts differences between priori information and extrinsic information. Unlike SCR, it requires no extra data storage. Simulations comparing technique with other well known criteria show proposed SDR scheme achieves similar performance in terms of bit error rate (BER), frame (FER), average number iterations, while requiring lower...

Abstract The design of complex aerospace systems is a multidisciplinary optimization (MDO) problem involving the interaction multiple disciplines. However, because necessity evaluating expensive black-box simulations, enormous computational cost solving MDO problems in has also become practice. To resolve this, metamodel-based techniques have been applied to MDO. With these methods, system models can be rapidly predicted using approximate metamodels improve efficiency. This paper presents an...

Advanced Air Mobility (AAM) has emerged as a pioneering concept designed to optimize the efficacy and ecological sustainability of air transportation. Its core objective is provide highly automated transportation services for passengers or cargo, operating at low altitudes within urban, suburban, rural regions. AAM seeks enhance efficiency environmental viability aviation sector by revolutionizing way travel conducted. In complex environment, traffic management control are essential...

Electric vertical takeoff and landing technology has emerged as a promising solution to alleviate ground transportation congestion. However, the limited capacity of onboard batteries enforces hard time constraints for vehicle operations in complex urban environment. Therefore, constrained, real-time trajectory optimization method is necessary enable safe energy-efficient flight. Unfortunately, most existing methods suffer from low computational efficiency, unpredictable convergence...

Abstract All-electric geostationary orbit (GEO) satellite systems design is a challenging multidisciplinary optimization (MDO) problem, which computation-intensive due to the employment of expensive simulations. In this paper, all-electric GEO MDO problem with multi-fidelity models investigated. The involving six inter-coupled disciplines formulated minimize total mass system subject number engineering constraints. To reduce computational cost analysis (MDA) process, transfer dynamics and...

Spacecraft system design is practically a complex multidisciplinary optimization (MDO) problem. Because of the application high-fidelity simulation models, massive computational cost spacecraft MDO problems becomes bottleneck and challenging problem in engineering practices. To address issue, this paper proposes novel filter-based sequential radial basis function (FSRBF) method for effectively efficiently solving problems. In FSRBF, to handle expensive constraints, filter constructed,...

The majority of the performance studies turbo codes presented in literature to date have assumed use floating point arithmetic. However, if fixed arithmetic is employed, a corresponding degradation BER decoding algorithm expected. In this paper, effects quantization and upon log-MAP APRI-SOVA algorithms for BPSK communication system are quantified via simulation. It shown that, with proper scaling signal prior quantization, no incurred eight-bit even four-bit can provide acceptable performance.

Abstract To further reduce the computational expense of metamodel-based design optimization (MBDO), a novel sequential radial basis function (RBF)-based method using virtual sample generation (SRBF-VSG) is proposed. Different from conventional MBDO methods with pure expensive samples, SRBF-VSG employs mechanism to improve efficiency. In proposed method, least squares support vector machine (LS-SVM) classifier trained based on real samples considering objective and constraint violation. The...

This letter studies the numerical properties of log-MAP-based soft-input soft-output decoding. The ranges differences between path metrics, soft output, and complete information are derived. Since log-MAP algorithm is functionally dependent only upon not their magnitudes, a module normalization technique that automatically implemented in two's complement arithmetic can be used to accommodate overflow metrics. An expression for minimum internal data width decoder employs As an application,...

This letter proposes a novel constraint-based 3G network planning model and hybrid approach for optimizing the problem. Computational results show that are more efficient than mathematical existing heuristics. Optimal solutions always obtained small medium sized problems. For larger problems, final on average within 5.77%-7.48% of lower bounds. The proposed can be an tool tackling wide range combinatorial NP-hard

View Video Presentation: https://doi.org/10.2514/6.2023-1742.vid In this paper, we propose a novel approach to optimal landing control of electric vertical takeoff and (eVTOL) vehicles for potentially wide applications such as urban air mobility (UAM), passenger transportation, package delivery, aircraft carrier missions. Our particular interest is develop efficient algorithms that facilitate generation accurate trajectories eVTOL under operational constraints considering high-fidelity...

View Video Presentation: https://doi.org/10.2514/6.2023-4499.vid Urban Air Mobility (UAM) promises a new mode of transportation system providing disruptive innovative operation safely and efficiently in highly constrained urban environment. The UAM is attracting interest from wide range stakeholders, institutions, businesses due to the technological advances electric distributed propulsion, which makes it easier construct unique aircraft types with capability for Vertical Take-off Landing...

To efficiently implement space debris removal missions on geostationary Earth orbit (GEO), a scheduling optimization scheme of multiple hybrid-propulsive servicing spacecraft (SSc) is proposed. In this scheme, many-to-many task allocation coding model established to formulate the sequences targets with respect different SSc. And transfer strategy developed maneuvers save propellant consumption and time simultaneously via using both electric chemical propulsion systems. Then, GEO problem...

We introduce algebraic machine reasoning, a new reasoning framework that is well-suited for abstract reasoning. Effectively, reduces the difficult process of novel problem-solving to routine computation. The fundamental objects interest are ideals some suitably initialized polynomial ring. shall explain how solving Raven's Progressive Matrices (RPMs) can be realized as computational problems in algebra, which combine various well-known subroutines include: Computing Gröbner basis an ideal,...

The development of Advance Air Mobility (AAM) is revolutionizing air transportation by introducing autonomous aircraft, particularly electric vertical takeoff and landing (eVTOL) vehicles, for efficient movement people cargo in urban remote areas. majority aircraft operating the AAM system are expected to be eVTOL which will utilize vertiports as their base operations. However, unlike traditional airports general aviation placement within densely populated areas poses distinct challenges...

Ground transportation in urban areas faces increasingly severe congestion; however, roads cannot be expanded unlimitedly. Under the air mobility (UAM) concept, electric vertical takeoff and landing (eVTOL) aircraft can use third dimension of space for various needs. However, energy required to complete an UAM mission by eVTOL vehicle must less than available stored battery pack. Furthermore, vehicles fly along feasible paths, such as avoiding collisions with any obstacles arrive at...

There are many aspects that have to be considered during planning phase of 3G networks. Some the most important factors are: quality service (QoS), cost implementation and provisioning, traffic coverage ratio, resource utilization. This paper analyzes mobile radio network deployment proposes optimization models which explicitly take into account some such as QoS power control. It also a tabu search algorithm solve overall problem NP-hard. Computational experiments with realistic sizes...

This paper proposes an efficient constraint-based optimization model for the design of 3G mobile networks, such as universal telecommunications system (UMTS). The concerns about finding a set sites locating radio network controllers (RNCs) from pre-defined candidate sites, and at same time optimally assigning node Bs to selected RNCs. All these choices must satisfy constraints optimize objective function. problem is NP-hard consequently cannot be practically solved by exact methods real size...