Optimal deployment of the spoke of a largesized transformable reflector according to the hierarchy of criteria

The article discusses the process of controlling the angular motion of the spoke of a large-sized space-based reflector, taking into account bending vibrations. Currently, large antennas are actively used for receiving and transmitting data. When launching large structures into space, the problem arises of reliably deployment the spokes, since they are packed in a small volume to be able to be installed in a launch vehicle. Due to the possibility of various abnormal situations, such as jamming of elements, engagement of the net, it is necessary to re-deployment the antenna. Therefore, it is important to develop control algorithms that can reliably solve the problems of direct and reverse motion. In the process of deployment and bringing together the elements of the reflector, various deformations appear in the structure. When the antenna spokes are brought together, lateral oscillations make the largest contribution to the oscillatory of the transient process. Currently, elastically deformed elements are used to deployment large-sized reflectors, and a control program is also used. This prevents the control from being adjusted when the deployment conditions change. The paper investigates the possibility of minimizing the vibrations of a structure during its deployment by using optimal control algorithms in real time. The forward and reverse motion of the antenna elements is performed by means of a two-criteria hierarchy optimization. The results of numerical simulation of the optimal rotation of the reflector spoke are presented. The proposed algorithm allows you to choose the optimal control in emergency situations for various types of large reflectors.

A Fast and Robust Rotation Search and Point Cloud Registration Method for 2D Stitching and 3D Object Localization

Rotation search and point cloud registration are two fundamental problems in robotics, geometric vision, and remote sensing, which aim to estimate the rotation and transformation between the 3D vector sets and point clouds, respectively. Due to the presence of outliers (probably in very large numbers) among the putative vector or point correspondences in real-world applications, robust estimation is of great importance. In this paper, we present Inlier searching using COmpatible Structures (ICOS), a novel, efficient, and highly robust solver for both the correspondence-based rotation search and point cloud registration problems. Specifically, we (i) propose and construct a series of compatible structures for the two problems, based on which various invariants can be established, and (ii) design time-efficient frameworks to filter out outliers and seek inliers from the invariant-constrained random sampling based on the compatible structures proposed. In this manner, even with extreme outlier ratios, inliers can be effectively sifted out and collected for solving the optimal rotation and transformation, leading to our robust solver ICOS. Through plentiful experiments over standard datasets, we demonstrated that: (i) our solver ICOS is fast, accurate, and robust against over 95% outliers with nearly a 100% recall ratio of inliers for rotation search and both known-scale and unknown-scale registration, outperforming other state-of-the-art methods, and (ii) ICOS is practical for use in real-world application problems including 2D image stitching and 3D object localization.

Price Premium Requirements for Growing Higher Quality Pine Sawtimber in Even-Aged Systems in the Southeastern United States

Intensive pine silviculture has become the dominant management paradigm in the southeastern United States. Although productivity has been substantially increased by the combination of cultural, silvicultural, and genetic advancements, wood quality is sometimes sacrificed in intensive silviculture. Extending the optimal rotation allows trees to grow more timber, which may result in the production of better quality sawtimber; however, landowners may require incentives to do so. We simulated loblolly, slash, shortleaf, and longleaf pine for growth and yield using the Forest Vegetation Simulator (FVS) to determine sawtimber price premiums landowners would require to offset the costs associated with delaying the final harvest by 10 to 30 years in even-aged systems. Required incentives increased with the length of harvesting delay beyond the financially optimal rotation age. On medium productivity sites, landowners would be willing to delay the final harvest by 10 years for sawtimber price premiums of $5.06/ton (20.47%) for loblolly, $5.34/ton (21.6%) for slash, $4.56/ton (18.45%) for longleaf, and $6.71/ton (27.14%) shortleaf pine, respectively. Harvest delays of 10 to 20 years were financially justifiable, whereas extensions exceeding 30 years were prohibitively costly for all species. Delaying the optimal harvest could benefit landowners by generating a premium price for their sawtimber while providing important ecosystem services. Study Implications The study findings will provide a baseline resource for forest landowners and managers who are interested in growing higher-quality and larger-diameter pine sawtimber to longer rotation ages to obtain a premium price. The results will also be helpful to primary forest product industries (e.g., sawmills) who prefer high-quality pine sawtimber and are considering offering a price premium for higher-quality pine sawtimber. Findings can be useful for those interested in managing forests for multiple benefits (e.g., timber production, wildlife hunting leases, carbon credits, and other ecosystem service incentives), as managing stands on longer rotations can provide the dual opportunities of receiving price premiums for higher-quality sawtimber while simultaneously generating revenue from nontimber benefits, which may help justify delaying the final harvest. Our findings can also help make policymakers and forest managers more aware of the minimum price premiums required to offset the revenue loss accrued by delaying the final harvest.

Multi-Item Production Lot Sizing with Postponement, External Source for Common Parts, and Adjustable Rate for End Products

This study considers a multi-item production lot-size problem incorporating postponement, an external source for common parts, and an adjustable-rate for end products. Dealing with product variety, timely requirements, and limited in-house capacity has led production managers to seek manufacturing schemes and utilization-reduction strategies that can help them meet customer needs, smoothen fabrication schedules, and lower overall manufacturing expenses. We propose a two-stage manufacturing scheme. The first stage produces common parts for multiproduct incorporating a partial supply from an outside contractor to reduce utilization/uptime. Stage two fabricates all end products using an adjustable-rate to reduce the uptime further. We build a model to characterize the problem’s features and use optimization methods to derive the optimal rotation cycle time in order to help managers make cost-effective lot-size decisions and allow manufacturers to gain competitive advantages. A numerical illustration validates the model’s capability and applicability. This study makes two important contributions: (1) It offers a decision-support model for studying such a particular batch-size problem and deciding the optimal rotation cycle time, and (2) it identifies the individual/collective influence of dual uptime-reduction strategies on the operating policy and various performance indexes to help facilitate managerial decision-making.

Low complexity channel estimation algorithm using paired spatial signatures for UAV 3D MIMO systems

This paper proposes a low complexity channel estimation algorithm for unmanned aerial vehicle three dimension multi-user multiple-input-multiple-output (3D MIMO) systems with the uniform planar array (UPA) at base station using paired spatial signatures. With the aid of antenna array theory and array signal processing, 3D channel is firstly modeled based on the angles between the direction of arrival along x- and y-axis of the UPA. And 3D MIMO channels can be projected onto the x- and y-directions, respectively. Then, channel estimation for multi-user uplinks using small amount of training resources is divided into two phases. At the first uplink preamble phase, each user is assigned the orthogonal pilot, and the paired spatial signatures and optimal rotation angle of each user through the same pilot sequence are obtained. We also propose a user grouping strategy based on three-dimension angle-division multiple access (3D-ADMA) to ensure that the user's spatial signatures do not overlap. At the second phase during several coherence times, the same pilot sequence within a group and orthogonal pilot sequences between groups are assigned, then, the channel state information of the user's x- and y-directions are recovered by the paired space signatures and optimal rotation angle of each user obtained in the preamble phase, respectively. And dynamically updating the user's paired spatial signatures and optimal rotation angle utilizes the obtained channel parameter of x- and y-directions. Finally, the channel parameter of the x- and y-directions are reconstructed by the updated user's space signatures and the optimal rotation angle, and the 3D MIMO channel estimation is obtained through the Kronecker product. Compared with the conventional channel estimation method of the 3D MIMO system under UPA using a low-rank model, the proposed methods reduce the computational complexity without degrading the estimated performance to a large extent. Furthermore, it is carried out with limited training resources, and the pilot resource overhead of the system is greatly reduced by the 3D-ADMA packet and the two-stage pilot allocation. Simulation results verified that the proposed algorithm is effective and feasible.

Diversity of Carbon Storage Economics in Fertile Boreal Spruce (Picea Abies) Estates

A “normal forest”, an idealized estate with a uniform distribution of stand ages, can be used in the study of sustainable management practices. As the normal forest contains a variety of stand ages, the characteristics of the stands can be represented in terms of a “normal stand”, with properties known as a function of age. This paper takes seven never-thinned stands as seven “normal stands”, which describe seven estates of normal forest. The intention is to study the robustness of carbon storage microeconomics to varying estate characteristics. It was found that the economically optimal rotation ages vary. The state sums of volume and capitalization, corresponding to any optimal rotation, also vary significantly. Growth rates vary more than the optimal expected stand volumes. Consequently, any excess volume related to carbon storage adds on to an almost unified basic volume. For all seven normal estates, the most economical way of increasing carbon storage is to increase the size of trees retained in thinning from above.

Experimental and theoretical study of the flocculants mixing in water

The article discusses the process of high molecular weight flocculant particles dissolving in water during mechanical stirring. A procedure of mixer selection taking into account mixer geometry based on the Prandtl’s semi-empirical turbulence model was developed and described. It was found that the choice of the optimal rotation speed is related with the turbulent frictional stress generated by the impeller of the mixer. The results of experimental studies on the preparation of concentrated solutions of high molecular weight cationic flocculant MagnaflokМ 155 using various impeller types are shown. The efficiency of a conical mixer has been confirmed, which makes it possible prepare a flocculant solution 1.3 times faster due to the possibility of mixing at higher rotational speeds with lower power consumption