Optimal Rotation Research Articles

A Novel Complex-Valued Blind Source Separation and Its Applications in Integrated Reception

The separation of time–frequency mixing signals composed of radar, communication, and jamming is the first step in integrated reception processing, which requires higher accuracy for complex blind source separation (CVBSS). However, traditional CVBSS methods have limitations such as low separation accuracy, a slow convergence speed, and poor robustness in low signal-to-noise ratio (SNR) and high jamming-to-signal ratio (JSR) scenarios. To address the above issues, this paper firstly establishes a time delay mixing mathematical model. A robust whitening algorithm is proposed by using the time delay correlation matrix of the observed signal, which is insensitive to noise. Secondly, the joint diagonalized F-parametrization is used as the objective function, and the separation matrix is constructed based on the multiple complex-valued Givens matrices. The complex-valued Givens matrix not only ensures orthogonality in the separation matrix but also effectively reduces the number of parameters to be calculated. This approach guarantees accuracy and simplifies the complexity of the separation process. Finally, the nonlinear chaotic grey wolf optimizer is utilized to search for the optimal rotation angle. The simulation results demonstrate that this algorithm offers higher separation accuracy and requires fewer iterations compared to the traditional algorithm. Additionally, it enhances the accuracy of direction of arrival (DOA) estimation, reduces the communication bit error rate, and enables the joint estimation of the target distance and velocity even in the presence of powerful jamming and a low SNR.

Control of the Rotation of a Solid (Spacecraft) with a Combined Optimality Criterion Based on Quaternions

The dynamic problem of the optimal rotation of a rigid body (for example, a spacecraft) from an arbitrary initial to a designated final angular position in the presence of restrictions on the control variables is studied. Rotation time is not fixed. To optimize the rotation control program, a combined quality criterion is used, the minimized functional combines the energy costs and the duration of the maneuver in a given proportion. Based on the L. S. Pontryagin maximum principle and quaternion models of controlled motion of a solid, a solution to the problem was obtained. The reorientation optimality conditions are written in analytical form, and the properties of optimal rotation are shown. To construct an optimal rotation program, formalized equations and calculation formulas are written. Optimal control is presented in the form of a synthesis. The control law is formulated as an explicit dependence of the control variables on the phase coordinates. Analytical equations and relations for finding the optimal motion are given. Key relationships are given that determine the optimal values of the parameters of the rotation control algorithm. A constructive scheme for solving the boundary value problem of the maximum principle for arbitrary rotation conditions (initial and final positions and moments of inertia of a rigid body) is also described. For a dynamically symmetric rigid body, a closed-form solution of the reorientation problem is obtained. A numerical example and the results of mathematical modeling are presented, demonstrating the practical feasibility of the developed method for controlling the attitude of a spacecraft.

Arduino uno-based electronic control unit module remapping to achieve optimal engine rotation speed on spark ignition 2-stroke direct injection engine

Direct injection technology in 2-stroke motorcycle engines can be a hope for overcoming exhaust emissions and optimizing ignition 2-stroke engine performance because direct injection engines use high-pressure pumps based on injection time and duration. On the TPS (throttle position sensor) to produce the optimal fuel mixture. This research will focus on Remapping the Arduino Uno-Based Electronic Control Unit (ECU) Module to Analyze Optimal Engine Rotation Speed in Spark Ignition 2-Stroke Direct Injection Machines. Experimental method using a Spark Ignition 2-Stroke Direct Injection engine with a capacity of 110cc. Variation of injection time angle 5°, 10°, and 15° Before BDC, 0° BDC, and 5°, 10°, and 15° after BDC, variations in injection duration based on TPS opening 20%, 40%, 60%, 80%, and 100%, as well as the fuel injected duration of 3ms, 3.25ms, 3.5ms, 3.75ms and, 4.25ms. Arduino module as a control system for timing and duration of fuel injection. Then tested alternately to get the optimal engine speed using a tachometer. Optimal results are obtained on the injection time curve 15 before BDC produces optimal engine speed with a value of 5480 rpm with a duration of 3.75 ms based on TPS openings of 61-80%.

Analysis of hydrofoil rotation control method for improving the propulsion performance of wave-powered boats considering the effect of currents

The wave-powered boat is a kind of mobile marine platform that can convert wave energy into thrust through the rotation of the hydrofoils. The rotation control method of the hydrofoil has a significant impact on the propulsion performance of wave powered-boats when considering ocean currents. In this paper, by establishing an equivalent instantaneous optimization model for the motion of the hydrofoil, the rotation angle that can obtain the maximum thrust is analyzed, and the relationship between the rotation angle, hydrofoil motion velocity as well as the current velocity is obtained. Subsequently, the propulsion performance of the hydrofoil under the active control method is compared with that under the passive control method through the fluid-multibody coupled analysis, and the motion parameters of the hydrofoil are explored, thus the feasibility of active control when considering the ocean currents is verified. It can be seen that the active control method based on the optimal rotation angle equation can significantly improve the propulsion performance of the wave-powered boat in the presence of currents. Under the passive control method, either increasing the stiffness or increasing the co-current velocity will make the rotation process of the hydrofoil fluctuate and disorderly. In contrast, the active control method can stabilize the rotation process of the hydrofoil, and the hydrofoil is always in a position where the maximum thrust can be obtained during rotation, thus making the propulsion performance better. The relevant research in this paper can provide a reference for similar research of the wave-powered boat.

Pengaruh Bentuk Impeller pada Proses Koagulasi Flokulasi Terhadap Pola Aliran dan Penyisihan TSS

Environmental pollution caused by wastewater has reached alarming levels, especially in large cities like Surabaya, where household wastewater is a major contributor. The coagulation-flocculation method is used to treat wastewater by precipitating particles from the wastewater. The use of mechanical impellers plays a crucial role in this process. This study analyzes the influence of impeller design, mixing time, and impeller rotation speed on the efficiency of Total Suspended Solid (TSS) removal and flow patterns in coagulation-flocculation. An impeller with a blade angle of 30° produces a wider and more effective flow pattern compared to a 60° angle. The number of blades and the blade angle affect TSS removal efficiency, with a 6-blade impeller at 30° angle achieving the highest efficiency. The optimal mixing time is 1 minute for coagulation and 20 minutes for flocculation. The optimal impeller rotation speed is 100 rpm for coagulation and 60 rpm for flocculation. The findings provide practical guidelines for enhancing the efficiency of domestic wastewater treatment.

Effective Mean Square Differences: A Matching Algorithm for Highly Similar Sheet Metal Parts.

The accurate identification of highly similar sheet metal parts remains a challenging issue in sheet metal production. To solve this problem, this paper proposes an effective mean square differences (EMSD) algorithm that can effectively distinguish highly similar parts with high accuracy. First, multi-level downsampling and rotation searching are adopted to construct an image pyramid. Then, non-maximum suppression is utilised to determine the optimal rotation for each layer. In the matching, by re-evaluating the contribution of the difference between the corresponding pixels, the matching weight is determined according to the correlation between the grey value information of the matching pixels, and then the effective matching coefficient is determined. Finally, the proposed effective matching coefficient is adopted to obtain the final matching result. The results illustrate that this algorithm exhibits a strong discriminative ability for highly similar parts, with an accuracy of 97.1%, which is 11.5% higher than that of the traditional methods. It has excellent potential for application and can significantly improve sheet metal production efficiency.

Annual Tree-Ring Curve-Fitting for Graphing the Growth Curve and Determining the Increment and Cutting Cycle Period of Sungkai (Peronema canescens)

Growth and increment are extremely important in sustainable forest management, and in forest inventory they are periodically measured in a permanent sampling unit. The age of a tree is often unknown, especially in natural, community, and urban forests; therefore, determining growth and increment can be problematic. The aim of this study was to propose a solution for this problem by conducting annual tree-ring curve-fitting to determine a tree’s age-related dimension so that growth and increment can then be calculated smoothly. Sungkai (Peronema canescens), a luxurious commercial timber chosen as a case study, resulted in a satisfying growth curve following continuous models (Gompertz, Chapman–Richards, and von Bertalanffy) and discrete models (Bahtiar and Darwis exponential modification). The Chapman–Richards model gave the best-fit sigmoid growth curve. The first derivation (dN/dt) of the growth formula produces the current annual increment (CAI). CAI intersection with mean annual increment (MAI) at the peak of MAI resulted in the optimum biological rotation age and a cutting cycle period of 30 years for the Sungkai plantation commonly planted in urban forests.

Conservation Agriculture: A Long-term Approach towards Sustainability

With the application of intensive agricultural techniques, conventional agriculture has been successful in meeting production goals but has also led to the depletion of natural resources. Sustainability in the management of the natural resource base is necessary for ongoing and expanded agricultural output to provide food security for future generations. Over a long period, the traditional tillage practice has led to the destruction of the natural resource base of the land. As a result of its inherent connection to the physical, chemical, and biological aspects of soil, it has led to a significant loss of soil and SOM, which is a crucial component of soil quality. Therefore, a suitable cropping system and land use must be implemented and adopted to ensure food security on a sustainable basis. These measures should be based on principles to prevent land degradation, protect the natural resource base, and improve food and nutritional security through crop diversification and optimal rotation. The one sustainable cropping method that may reverse soil erosion, increase crop output, and improve the socioeconomic status of small landholder farmers is conservation agriculture (CA). Conservation agriculture (CA) is the integrated management of the available natural resources such as soil, water, flora, and fauna, with certain outside inputs to maximize the effectiveness of natural resource utilization. To fulfill the objective of sustainable crop production, an alternative approach known as conservation agriculture has emerged. It represents a significant advance in the direction of sustainable agriculture. This article reviews the emerging concerns due to the continuous adoption of conventional agriculture systems, contrasting features between conventional and conservation agriculture systems, and various principles and practices in conservation agriculture. It also highlights the benefits and limitations of CA and various challenges in the adoption of CA.

Research and Experiment on Variable-Diameter Threshing Drum with Movable Radial Plates for Combine Harvester

In order to solve the problem of the threshing performance of a large combine harvester being reduced due to the non-adjustable diameter of the threshing drum, a variable-diameter threshing drum with movable radial plates based on the principle of concentric regulation was studied. It was mainly composed of a mechanism for adjusting the diameter by moving the radial plates, six fixed threshing tooth rods, six retractable threshing tooth rods and the single piston rod hollow hydraulic cylinder. The threshing gap can be adjusted by a stepless change of the drum diameter. By using RecurDyn simulation and field performance tests, the adjustable ranges of diameter and gap of the movable variable-diameter threshing drum were 670~710 mm and 10~30 mm. Based on the feed amount of the combine, the rotation speed of the threshing drum and the threshing gap (the diameter of the drum) as the influencing parameters, and the grain entrainment loss rate, grain un-threshed rate and grain breakage rate as the evaluation indexes, the three-factor and three-level response surface tests were carried out, and the result data were analyzed using Design-Expert 13.0. The optimal threshing gap and rotation speed of the threshing drum were determined under different feeding quantities. A comparative test was carried out to adjust and fix the threshing gap and rotation speed of the threshing drum in real time according to the change in feeding amount. The results showed that when the working parameter combination under different feeding amounts was adjusted in real time, the entrainment loss rate was 0.65%, the un-threshed rate was 0.063% and the breakage rate was 0.47%. Compared with the threshing gap and the rotation speed of the threshing drum being fixed, the entrainment loss rate, the un-threshed rate and the breakage rate were reduced by 44.9%, 27.6% and 34.1%, respectively. A threshing drum with variable diameter was provided for a large multi-crop harvesting combine to realize the concentric stepless adjustment of the threshing gap.

Fast and Accurate Refocusing for Moving Ships in SAR Imagery Based on FrFT

Synthetic aperture radar (SAR) is capable of monitoring the ocean all day, regardless of weather conditions. However, moving ships exhibit azimuth defocus in SAR images, which severely hampers ship recognition performance. Ships typically move in a linear motion at sea. For refocusing linear moving ships, existing SAR autofocus algorithms cannot accurately extract defocus information and require multiple iterations. To overcome the poor focusing quality and high computational complexity of existing refocusing algorithms, this paper proposes a fast and accurate refocusing scheme for moving ships in SAR imagery based on Fractional Fourier Transform (FrFT). Firstly, the azimuth line with the strongest energy in the SAR image is selected as the best azimuth line representing its motion property. Then, according to the entropy variation law of the azimuth line after FrFT, the azimuth line’s optimal rotation order is determined by the proposed minimum entropy search method, which can accurately and quickly obtain defocus information. In the final refocusing module, the scheme provides two ways, i.e., fast or fine refocusing approaches, to generate well-focused images. The fast refocusing approach performs FrFT on each azimuth line at the optimal rotation order of the best azimuth line. The fine refocusing approach takes the optimal rotation order of the best azimuth line as the initial value and further searches for the optimal rotation order of other azimuth lines. In order to verify the effectiveness of the proposed scheme, experiments are carried out on a number of Gaofen-3 SAR images in different acquisition modes. The experimental results show that the proposed fast refocusing approach can achieve the fastest speed, which is 2.1% of the traditional FrFT-based method’s processing time. Moreover, the proposed fine refocusing approach has the best focusing performance, achieving the lowest image entropy among existing methods.

High-Efficiency Wide-Angle Scanning Mechanoelectrical Hybrid Phased Array Antenna With Mechanically Reconfigurable Element Pattern

In this paper, a high-efficiency wide-angle scanning mechanoelectrical hybrid phased array antenna with mechanical-ly reconfigurable element pattern is proposed. The proposed array is composed of several linear array panels, which can be mechanically rotated. In contrast to conventional hybrid scan-ning arrays, it rotates in the elevation plane with only three fixed states enabling quick beam switching capabilities, rather than constantly rotating in the azimuth plane. The optimal element's half power beam-width (HPBW) and panel rotation angle are examined in this paper to produce the best scanning range and gain performance in the rotation plane for the array. As a proto-type, an 8×8 array formed by an equivalent magnetic dipole patch antenna, whose HPBW is properly designed to satisfy the optimal value, is configured and fabricated. Both simulated and experimental results show that the proposed array can scan its main beam from -67° to 67° in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">yoz</i> plane, -75° to 75° in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xoz</i> plane, and its 3-dB beam coverage reaches ±82°, ±90° in the two planes. Additionally, the peak efficiency of the array can reach 75%.

Giant, magnet-free, and room-temperature Hall-like heat transfer

Thermal chirality, generically referring to the handedness of heat flux, provides a significant possibility for modern heat control. It may be realized with the thermal Hall effect yet at the high cost of strong magnetic fields and extremely low temperatures. Here, we reveal magnet-free and room-temperature Hall-like heat transfer in an active thermal lattice composed of a stationary solid matrix and rotating solid particles. Rotation breaks the Onsager reciprocity relation and generates giant thermal chirality about two orders of magnitude larger than ever reported at the optimal rotation velocity. We further achieve anisotropic thermal chirality by breaking the rotation invariance of the active lattice, bringing effective thermal conductivity to a region unreachable by the thermal Hall effect. These results could enlighten topological and non-Hermitian heat transfer and efficient heat utilization in ways distinct from phonons.

Response of Soil Microbial Community Diversity to Long-Term Cultivation of Rice (Oryza sativa L.)/Cherry Tomato (Lycopersicon esculentum Mill.) in Rotation

The crop rotation periodicity has always been a concern of agricultural researchers. This study was the first investigation on the effects of long-term continuous cultivation with rice/cherry tomato rotation on soil microbial community diversity. The main objective was to analyze the optimal rotation years of rice/cherry tomato from a micro-ecology perspective so as to provide theoretical basis for effectively avoiding continuous cropping obstacles of cherry tomato. Soil samples were collected from the surface layers with rice/cherry tomato rotations for 1 year (1a), 3 years (3a), 5 years (5a), 7 years (7a) and 10 years (10a). The microbial community diversity was determined via high-throughput sequencing. The results showed that alpha diversity of soil microbial communities was the highest at 5a and then gradually decreased during 5a to 10a. Beta diversity results revealed that microbial community structure was significantly different among 1a, 3a to 7a and 10a, but there were no clear differences among 3a, 5a and 7a. The abundances of soil beneficial bacteria Gemmatimonadetes, Bacteroidetes, Chloroflexi, Nitrospirae and beneficial fungi Mortierella, Trichoderma, Penicillium were the highest at 5a or 7a. Those of soil pathogenic fungi Fusarium and Aspergillus were the lowest at 5a and 7a, respectively. However, the relative abundances of the above-mentioned beneficial microorganisms began to decline, while those of pathogenic fungi began to increase after 5a or 7a. Soil available phosphorus, available iron and available zinc were common important factors affecting the community structure of bacteria and fungi, as indicated by significant positive correlations between the environmental factors and microbial communities. In conclusion, the soil microbial diversity began to decline and the micro-ecological balance was broken after continuously planting 5a to 7a with rice/cherry tomato rotation, which would lead to new continuous cropping obstacles.

Refocusing Swing Ships in SAR Imagery Based on Spatial-Variant Defocusing Property

Synthetic aperture radar (SAR) is an essential tool for maritime surveillance in all weather conditions and at night. Ships are often affected by sea breezes and waves, generating a three-dimensional (3D) swinging motion. The 3D swing ship can thereby become severely defocused in SAR images, making it extremely difficult to recognize them. However, refocusing 3D swing ships in SAR imagery is challenging with traditional approaches due to different phase errors at each scattering point on the ship. In order to solve this problem, a novel method for refocusing swing ships in SAR imagery based on the spatial-variant defocusing property is proposed in this paper. Firstly, the spatial-variant defocusing property of a 3D swing ship is derived according to the SAR imaging mechanism. Secondly, considering the spatial-variant defocusing property, each azimuth line of the SAR 3D swing ship image is modeled as a multi-component linear frequency modulation (MC-LFM) signal. Thirdly, Fractional Autocorrelation (FrAc) is implemented in order to quickly calculate the optimal rotation order set for each azimuth line. Thereafter, Fractional Fourier Transform (FrFT) is performed on the azimuth lines to refocus their linear frequency modulation (LFM) components one by one. Finally, the original azimuth lines are replaced in the SAR image with their focused signals to generate the refocused SAR image. The experimental results from a large amount of simulated data and real Gaofen-3 data show that the proposed algorithm can overcome the spatial-variant defocusing of 3D swing ships. Compared with state-of-the-art algorithms, our approach reduces the image entropy by an order of magnitude, leading to a visible improvement in image quality, which makes it possible to recognize swing ships in SAR images.

Rotation invariant GPS trajectory mining

Mining of GPS trajectories of moving vehicles and devices can provide valuable insights into urban systems, planning and operational applications. Understanding object motion often requires that the spatial-temporal matching of trajectories be invariant to shifting, scaling and rotation. To this end, Procrustes analysis enables to transform one data set of a trajectory to represent another set of data as closely as possible. We propose a novel shift-scale-rotation invariant Procrustes distance metric based on the Kabsch algorithm, which calculates the optimal rotation matrix by minimizing the root-mean squared deviation between two paired sets of points of trajectories or trajectory segments. We present two novel runtime efficient algorithms which are based on our proposed distance metric: 1) the sliding-shifting-scaling-Kabsch-rotation (S3KR) algorithm for detecting recurring short query patterns in longer motion trajectories and 2) a novel time series subsequence clustering algorithm to group GPS trajectory data and to discover prototypical patterns. We demonstrate the potential of our proposed sliding Procrustes analysis algorithms by applying it on real-world GPS trajectories collected in urban and rural areas from different transport modes, as well as on nautical GPS trajectories. We also demonstrate that our methods outperform the state of the art in accuracy and runtime on synthetic and real world data.

Laurel Regeneration Management by Smallholders to Generate Agroforestry Systems in the Ecuadorian Amazon Upper Basin: Growth and Yield Models

Laurel (Cordia alliodora Ruiz &amp; Pav. Oken) is a Neotropical native tree that is easily regenerated in the secondary forest within the Amazon region. Amazonian smallholders use this tree regeneration to obtain a homogeneous forest cover when developing local agroforestry systems, which do not depend on nursery seedling production for tree planting. The objective of the present investigation was to develop growth and yield models for Laurel within the local agroforestry systems. A total of 226 sampling plots were measured between 2010–2011 and 2014–2015. Chapman- Richard, Hosslfeld II, and the generalized algebraic difference approach (GADA) form of the Chapman-Richard’s function was used for modeling height-age and diameter-age relationships. Eight volume models were tested to describe total stem volume. The GADA method was suited to describe the Laurel height and diameter-age growth. The cutting cycle for agroforestry systems with a density of 300 trees ha−1 at the best site index (SI) (22 m) produced 13.9 m3 ha−1 year−1 and a total wood yield of 195.1 m3 ha−1 at age 14. In the worst SI (14 m), the average annual yield was 3.5 m3 ha−1, with a total yield of 83.3 m3 ha−1 at age 24 years. The Spurr potential model was the best fit to describe the volume of the Laurel according to the Akaike information criteria. The Laurel biological (optimal) rotation age suggests that the minimum cutting diameter should be lowered from 30 cm of DBH in the research zone. Management of the natural regeneration of secondary forests by smallholders is a local agroforestry practice that should be given greater attention, especially within protected forest areas.

On the uncertainty in estimates of the carbon balance recovery time after forest clear-cutting.

An essential metric for describing carbon dynamics in managed forest landscapes is the recovery time of the carbon balance after clear-cutting. Here, we demonstrate how the age-dependent mathematical trajectory is affected by both the selected model and data availability, leading to considerable uncertainty in the modelling of the net ecosystem production (NEP) over stand age. We further show that the initial carbon loss estimates associated with the timing of the source-sink transition (SST) are significant, but may have a limited effect on the total carbon sequestration at the end of the standard (RP, 120 years) or optimal (OCS) rotation periods.

Dynamic optimization of formation and pace in a cycling team time trial considering effects of drafting and cyclists’ fatigue and recovery

This paper proposes a dynamic formation optimization approach to cycling team time trials, taking into account road elevation, drafting effects, and fatigue and recovery of the cyclists. Dynamic models of fatigue and recovery are those proposed in authors’ earlier work and calibrated using human subject data. The formation optimization problem is first solved for a team of two cyclists, with insights then used to formulate the problem for the more complex and general n-cyclist case. A mixed-integer nonlinear program formulation is proposed to determine the optimal position rotation strategy in addition to optimal power and velocity trajectory of the platoon. Simulation results show improved time compared to a baseline strategy that is popular among cycling teams.

Forest Land Expectation Value or Maximum Sustained Yield? Resolving A Long-Standing Paradox

The Faustmann formula, equivalent to the land expectation value (LEV), yields the present value, starting with bare land, of an infinite series of future timber rotations for a stand. If this formula is used to find the rotation age that maximizes the present value, a lower annual harvest will result when compared to a maximum sustained yield (MSY) regime for an ownership with many stands. However, the LEV is strongly preferred by economists. This is the LEV vs. rents paradox. Herein, this paper demonstrates that an infinite series of annual harvests for an ownership under an even flow regime, discounted to the present using any interest rate, will provide the same optimal rotation age as the time of the peak MAI for a single stand, though with different estimates for the profitability, depending on the interest rate. Thus, rotations producing the MSY and the maximum financial return are identical when analyzed at the ownership scale but are not the same when based on the analysis at the stand scale using the Faustmann formula (LEV). This is the solution to the paradox. The formulas for internal rate of return (IRR) and the land valuation for transaction purposes are also presented.

Wood product differentiation in age-structured forestry

We develop the classic market-level, age-structured forest model by extending the description of forestry output from homogenous wood to a set of differentiated outputs such as sawlogs and biofuels. The extension changes several most established results on the long-run sustainable market equilibrium of forestry. We show the existence of an optimal steady state with two (or more) simultaneous rotation periods. This equilibrium yields a smooth timber flow without normal forest structure and thus deviates from existing normal forest results as well as results on equilibrium cycles. We further show that the optimal rotation structure depends on wood product demand and the demand for land outside forestry, another feature that is absent in previous model formulations.