Direct Angle Research Articles

Optimizing DFIG‐DC system performance via model predictive control: Torque ripple, DC voltage drop, and THD reduction

AbstractIn this study, two novel control methods are theoretically introduced as direct slip angle control (DSAC) and model predictive direct slip angle control (MPDSAC) for rotor side converter (RSC) of the standalone Doubly‐Fed Induction Generator (DFIG)‐DC system (S‐DFIG‐DC). The numerical analysis of the proposed methods demonstrated that the proposed DSAC method could reduce torque ripple and current harmonics, decrease the output DC voltage drop in fast changes of load condition, and have faster dynamic response. Also, the MPDSAC method could further diminish torque and flux ripple, current harmonics, and output DC voltage drop in sharp changes of load condition compared with the presented DSAC and direct torque control (DTC) methods. The sensitivity analysis of the proposed control methods is investigated at different operating conditions. The performance and usefulness of the DSAC and MPDSAC schemes are verified by various experiments and compared with the conventional DTC method.

Osteotomy wedge angle - Aiming to achieve perfection with new device: Pre-clinical stage

IntroductionThe surgical execution of osteotomy requires precision in measuring the wedge angle. The pre-operative planning methods are plenty and so are few devices for high tibial osteotomy. But struggle happens for those bony areas other than proximal tibia where alignment correction is needed. The new device is proposed to address this surgical problem. The ease of measuring angle for bony wedge angle, in any bone, independent of its width and in any plane, is the question being solved with the proposed devices. MethodsTwo jig instruments have been shown in the study. First one the curved with direct angle measuring marking in degrees on the body. K wire is accepted through the tower exactly showing the desired angle. The second jig instrument is flat design with marking in millimeters. This device works on trigonometric principle of sum of angles of any triangle is equal to 180°. The jig can be removed leaving the k wires in place to complete the final osteotomy once confirmed. ResultsIt's a pre-clinical stage study. The saw bone models show encouraging measurements and perfect execution of angle at the osteotomy site. DiscussionHTO has been researched a lot with many options of surgical devices. The criticism of using known devices is the variable accuracy, especially for the smaller width of tibial metaphysis. One major limitation of these available instruments is they can be used only for proximal tibial metaphysis. For any other surgical sites like distal femur, distal tibia, distal humerus or tibial slope correction neither these HTO jigs will work nor there is any available universal instrument as such. The common misconception of one degree equal to 1 mm does not stand true at all bony sites. Hence there was a need to solve this problem with universal jig. I have designed two new devices which are currently at pre-clinical stage. The curve device has limitations which get corrected in straight device. The philosophy changes from one direct measurement with two tips of wires forming the angle in a curved device to indirect measurement by simple trigonometric calculation in a straight device. The proposed new device would work in any bone, for any trapezoidal wedge shape osteotomy using simple user-friendly k wires.

Laboratory assessment of shear strength parameters of sand amended via subsequent biopolymer-based soil treatment and enzyme-induced calcite precipitation combinations

Current ground improvement practices predominantly rely on cement; however, interest in strengthening the ground in an environmentally sustainable manner is growing due to concerns regarding the environmental impact, such as the high CO2 footprint associated with cement usage. Biopolymer-based soil treatment (BPST) and enzyme-induced calcite precipitation (EICP) have emerged as promising methods for environmentally friendly ground improvement. While several studies have demonstrated the effectiveness of BPST and EICP individually, both methods have their limitations, which can be seen as complementary (for instance, EICP is more effective for coarse soils, whereas BPST is more effective for clayey soils). Recently, efforts have been made to combine BPST with EICP to address these limitations. This study considered four consecutive BPST-EICP combinations: 1) EICP alone, 2) BPST alone, 3) pre-EICP followed by post-BPST, and 4) pre-BPST followed by post-EICP. Laboratory experiments were conducted to assess the shear strength parameters (i.e., direct shear cohesion and friction angle) of sand treated using these four methods. The peak and residual shear strength parameters of the pre-EICP followed by post-BPST soil were the highest among all cases. However, each combination is suited to specific site conditions, such as soil type, groundwater conditions, and the purpose of ground improvement.

Evaluating the sensitivity of direct shear testing of soils for rheological characterization of masonry mortars

The present work evaluated the applicability of the direct shear test of soils (ASTM D 3080) as an alternative for the rheological characterization of masonry mortars. The sensitivity analysis of the method for mortars was carried out by varying the particle size distribution of the sand and the water/dry material ratio, generating twelve different mixtures. In addition to a basic characterization, the shear test results were compared with those of the squeeze-flow test (ABNT NBR15839). For squeeze-flow, 24 tests were carried out with two speeds (0.1 and 3 mm/s), and for direct shear, 48 tests were carried out with 4 normal stresses (13.5, 25, 50, and 100 KPa). It is concluded that the direct shear test, using cohesion and friction angle parameters, demonstrated the ability to adequately characterize the complex behavior of plastic mortars and the sensitivity to variations in the mixture. A linear correlation was found between the friction angle (shear test) and the consistency index (flow table), with R2 = 0,87. Furthermore, for high plasticity mortars, was found a non-linear correlation between compression flow (squeeze flow) and cohesion (direct shear test), with R2 = 0,67.

Analogue magnitude representation of angles and its relation to geometric expertise

The distance effect (comparing objects becomes easier with increasing differences in their magnitude) is observed in tasks ranging across domains, and its existence has been interpreted as evidence for analogue magnitude representation. Similarly, associations between response side and magnitude (faster left/right-sided responses to small/large objects, respectively) are observed across domains. We investigated the analogue processing of angles and the association between angle magnitude and response side in relation to geometric expertise. We compared the behavioural pattern of two groups—architects and controls—in a direct angle magnitude classification task (i.e., judge whether a presented angle was greater or less than 90°) and in an indirect task (i.e., judge whether an angle was drawn with a dashed or continuous line). We found a robust distance effect for reaction times and accuracy at the whole sample level and in each group separately. Architects revealed a smaller distance effect for accuracy than controls. This could be interpreted as an argument for a more precise analogue representation of angles in experts compared to non-experts. However, we did not find evidence for an association between angle magnitude and response side in any group.

Chemical composition of soil humin in an organic soil profile

Humin is identified as the most recalcitrant fraction of soil organic matter, but its synthesis and depth variability in the soil profile are unknown. Here, we suggest that carboxyl-rich alicyclic structures (CRAM) and fused aromatic ring structures (FAR) can process significant components of the humin structure. We conducted molecular-level characterization of humin using advanced solid-state nuclear magnetic resonance spectroscopy (SSNMR) experiments and calculated the proportion of FAR and functionalities of CRAM (OCq, –C(CH)n, –CH3) structures. Dipolar dephased (dd) direct polarization magic angle spinning (DPMAS) NMR experiments provided insights into non-protonated carbon and mobile quaternary carbons. We calculated the proportions of non-protonated aromatic carbon and non-polar aliphatic C in the organic layers of the topsoil (Oa), mid-soil (Om), and mineral subsoil (Cg). It was evident that the total aliphatic carbon constitutes a significant proportion of humin, as is the non-protonated C attached to CH3. The 13C dd/DPMAS NMR spectrum of Cg humin clearly showed the formation and preservation of hydrophobic OCq, which is indicative of CRAM structures. CRAM structures could be attached to FAR, which makes the whole structure relatively more hydrophobic, a critical humin functionality in deeper soil. The findings from our research can be successfully utilized in terrestrial carbon sequestration studies to amplify the potential of humin as a recalcitrant carbon reservoir.

MOLECULAR DYNAMIC STUDY OF THE CRATERING PROCESS DURING HIGH-VELOCITY IMPACT OF METALLIC CLUSTERS WITH A SUBSTRATE

In the presented work, numerical experiments were carried out in the framework of the molecular dynamics method to study the impact interaction of metallic nanoclusters of different sizes with a metallic substrate in a wide range of velocities. Analysis of the obtained data showed that the crater volume remains proportional to the impact energy and inversely proportional to the dynamic strength of the material, with the direct angle coefficient being independent of the cluster size and the cluster-substrate material.

Deep learning-based estimation of whole-body kinematics from multi-view images

It is necessary to analyze the whole-body kinematics (including joint locations and joint angles) to assess risks of fatal and musculoskeletal injuries in occupational tasks. Human pose estimation has gotten more attention in recent years as a method to minimize the errors in determining joint locations. However, the joint angles are not often estimated, nor is the quality of joint angle estimation assessed. In this paper, we presented an end-to-end approach on direct joint angle estimation from multi-view images. Our method leveraged the volumetric pose representation and mapped the rotation representation to a continuous space where each rotation was uniquely represented. We also presented a new kinematic dataset in the domain of residential roofing with a data processing pipeline to generate necessary annotations for the supervised training procedure on direct joint angle estimation. We achieved a mean angle error of 7.19° on the new Roofing dataset and 8.41° on the Human3.6M dataset, paving the way for employment of on-site kinematic analysis using multi-view images.

Which power cycle is the best fit for parabolic trough solar collectors? A comparative and comprehensive case study for six sub-configurations of the three main cycles

In this study, the integration of a Parabolic Trough Collector with different power cycles was investigated on an annual basis in terms of Energy, Exergy, Economics and Environmental under different meteorological conditions. A parabolic trough collector with 500 collectors with a gross and net aperture area of 432,000 and 817.43 m2, was installed in a place that has a high solar energy potential. With a Parabolic trough collector, hourly Direct Normal Irradiation, wind speed, wind direction, ambient temperature and incident angle values were obtained for the 15th of each month for a year. The performance of the 3 power cycles with 6 different configurations using the Parabolic trough collector as the heat source was comprehensively analyzed and compared. During the dynamic data use and various commonly used power systems comparing study, it was aimed to answer the most commonly asked questions by the researchers in this area. To do this, the effect of direct normal irradiation and incident angle on the performance of systems to reach the maximum net power was studied. After calculations, the maximum net power was not found on July 15 (12:00) when the maximum direct normal irradiation (840.868 W/m2) was seen. The maximum net power (67867 kW) was found on September 15 (12:00) when the incident angle was minimum (1.71°) along with the high direct normal irradiation. Steam Rankine Cycle, Organic Rankine Cycle and Kalina Cycle performance comparisons were made both annually depending on time and with different configurations and fluids. In addition to tangibly showing the superiority of incident angle on direct normal irradiation, the present study aimed to present the best-performing system configuration for the researcher, user, scientists, and manufacturers. Interestingly, while the Organic Rankine Cycle with heat exchanger with R123 showed better performance in terms of power production and carbon dioxide emission reduction, the Kalina Cycle was found much more feasible in terms of economics.

Context-Aware Statistical Dead Reckoning for Localization in IoT Scenarios.

The current trends in 5G and 6G systems anticipate vast communication capabilities and the deployment of massive heterogeneous connectivity with more than a million internet of things (IoT) and other devices per square kilometer and up to ten million gadgets in 6G scenarios. In addition, the new generation of smart industries and the energy of things (EoT) context demand novel, reliable, energy-efficient network protocols involving massive sensor cooperation. Such scenarios impose new demands and opportunities to cope with the ever-growing cooperative dense ad hoc environments. Position location information (PLI) plays a crucial role as an enabler of several location-aware network protocols and applications. In this paper, we have proposed a novel context-aware statistical dead reckoning localization technique suitable for high dense cooperative sensor networks, where direct angle and distance estimations between peers are not required along the route, as in other dead reckoning-based localization approaches, but they are obtainable from the node's context information. Validation of the proposed technique was assessed in several scenarios through simulations, achieving localization errors as low as 0.072 m for the worst case analyzed.

Reflection of Acoustic Waves Falling Under a Direct Angle on a System of Flat Layers of a Vapor-Gas-Droplet Mixture with Solid Particles

Reflection of Acoustic Waves Falling Under a Direct Angle on a System of Flat Layers of a Vapor-Gas-Droplet Mixture with Solid Particles

Millimeter Wave Attenuation Due to Wind and Heavy Rain in a Tropical Region.

Millimeter wave fixed wireless systems in future backhaul and access network applications can be affected by weather conditions. The losses caused by rain attenuation and antenna misalignment due to wind-induced vibrations have greater impacts on the link budget reduction at E-band frequencies and higher. The current International Telecommunications Union Radiocommunication Sector (ITU-R) recommendation has been widely used to estimate rain attenuation, and the recent Asia Pacific Telecommunity (APT) report provides the model to estimate the wind-induced attenuation. This article provides the first experimental study of the combined rain and wind effects in a tropical location using both models at a frequency in the E band (74.625 GHz) and a short distance of 150 m. In addition to using wind speeds for attenuation estimation, the setup also provides direct antenna inclination angle measurements using the accelerometer data. This solves the limitation of relying on the wind speed since the wind-induced loss is dependent on the inclination direction. The results show that the current ITU-R model can be used to estimate the attenuation of a short fixed wireless link under heavy rain, and the addition of wind attenuation via the APT model can estimate the worst-case link budget during high wind speeds.

Determination of Sessile Drop Wetting Angle Based on μCT without the Direct Angle Measurement.

Wettability is an important factor that controls the position and transport of fluids in the porous structure of a hydrocarbon reservoir. Direct quantitative wettability measurement methods include determination of the contact angle. One of the popular laboratory methods for its measurement is the sessile drop method, where the droplet of liquid is set onto the solid sample surface and the angle between liquid and solid phases in a 2D profile image is measured using a high-resolution optical subsystem. However, this method has disadvantages connected with three complex factors: two-dimensionality of data, image resolution, and the presence of wetting domains on the solid surface. In this work, we propose a method based on 3D μCT scanning of a sessile drop on the surface of a material and determination of the value of the wetting angle using drop height and volume measurements. Since the contact angle is not measured directly, this makes it possible to obtain averaged contact angle values for the entire droplet and leads to more stable values for individual measurements in comparison with the standard optical method. The results demonstrate that contact angles obtained using the μCT method differ from the values obtained by various fitting techniques of the 2D optical method: μCT-values are higher for hydrophilic interaction by 4-6° and lower for hydrophobic interaction by 12-17°. Such differences are associated with the lower susceptibility of the proposed method to the influence of the gravitational effect, which leads to a flattening of the droplet shape and distortion of angle measurements on the 2D projections. However, the described method showed close contact angles for water drops on a polytetrafluoroethylene surface with values obtained in microgravity and can be helpful for its prediction. It also has relatively low sensitivity to the absolute values of the drop volume and drop segmentation errors.

Measuring direct and indirect tendon parameters to characterize the proximal tendinous complex of the rectus femoris in football and futsal players.

Objective: To present unprecedented radiological parameters that characterize the angle between the direct and indirect tendons of the proximal rectus femoris (RF) and its inclinations and to evaluate the population variability according to demographic variables. Materials and methods: From September 2019 to July 2021, using MRI multiplanar reconstructions of the proximal thigh/hip, two blinded radiologists measured the direct and indirect tendon angle and the inclination of each tendon in different planes. The intra- and inter-observer agreements were assessed with Bland-Altman analysis and intraclass correlation coefficient (ICC). The correlations between radiological parameters and demographic variables were evaluated using linear regression, Student's t-test, and analysis of variance. Results: We performed 112 thigh/hip MRI scans on 91 football players of different age, gender, and disciplines (football and futsal). For observer 1 (the reference), the mean direct and indirect tendon angle was 56.74° ± 9.37, the mean indirect tendon slope was -7.90° ± 7.49, and the mean direct tendon slope was 22.16° ± 5.88. The three measurements showed inter- and intra-observer agreement (mean differences ∼0). No correlation was observed between age and the parameters. Likewise, no statistically significant differences were found for gender, dominant limb, examined limb, and sport. Conclusion: There is an inter- and intra-observer agreement in the measurements of the direct and indirect tendon angle and the inclination of each tendon. There is population variability in the proximal tendinous complex unrelated to demographic factors. These results allow further detection of morphological patterns that represent a risk factor for lesions in the RF in professional football and futsal players and other sports.

A discrete differential evolution with local search particle swarm optimization to direct angle and aperture optimization in IMRT treatment planning problem

Intensity-modulated radiation therapy is a well-known technique for treating cancer patients worldwide. A treatment plan in this technique requires decision-making for three main problems: selection of beam angles, intensity map calculation, and leaf sequencing. Previous works investigated these problems sequentially. We present a new integrated framework for simultaneous decision-making of directions, intensities, and aperture shape, called direct angle and aperture optimization, and develop a mixed-integer nonlinear mathematical model for the problem. Due to the nonlinearity and the dimension of the problem, three efficient metaheuristics based on differential evolution (DE) called classic differential evolution (cDE), discrete differential evolution (dDE), and adaptive hybrid discrete differential evolution-particle swarm optimization (ahdDE-PSO) algorithms are designed to solve the problem. Parameters calibration is performed using the Taguchi design of experiments. The performance of the algorithms is evaluated by solving the problem for ten real cases of liver cancer disease from the TROTS data set. The performed ablation study and statistical analysis of computational results demonstrate that ahdDE-PSO is capable of finding high-quality treatment plans.

Analysis and Optimization of Parabolic Trough Solar Collector to Improve Its Optical Performance

Abstract This article presents a detailed analysis of parameters that affect the optical performance of parabolic trough solar collector (PTSC) and proposes a suitable method to optimize the relevant ones. A mathematical model is drafted and simulated for known geometry and parameters of industrial solar technology (IST) PTSC. The model was evaluated for three different configurations of IST PTSC involving distinct components. A comparison between the experimental results and model estimations indicates a maximum root-mean-square error (RMSE) of 0.7997, confirming the reliability of the proposed model. The influence of variations in absorber diameter (Dao), length (lrc), width (wrc), and focal length of PTSC (frc), along with direct normal incidence (In), dirt factors (ξdm, ξdhc), and angle of incidence (θ) on the optical performance of PTSC has been investigated. It was established that variation in mentioned parameters exhibits both positive and negative impacts on optical performance. After careful analysis, lrc, wrc, frc, Dao, and θ were chosen for optimization as it was perceived that by varying these in a reasonable range, an optimal set of parameters could be obtained that maximize the absorbed solar irradiation for a given PTSC. Genetic algorithm (GA), particle swarm optimization (PSO), and African vultures optimization algorithm (AVOA) are utilized to estimate the optimal values of parameters. Significant improvement in absorbed solar irradiation (∼16%) is registered with optimized parameters, suggesting that benefits can be obtained if a study is performed prior to producing PTSC modules for an application.

Incidence and Risk Factors for Secondary Glaucoma in Eyes with Uveal Melanoma

To estimate incidence of and analyze risk factors for developing secondary glaucoma in eyes with uveal melanoma before and after diagnosis. A cross-sectional, population-based cohort study. Seven hundred eighty-one patients (median age, 64 years; range, 14-93) consecutively diagnosed with uveal melanoma from 1997 to 2012 in a national ocular oncology service, 708 (91%) of whom received ruthenium (50%) or iodine (50%) brachytherapy. Patient, tumor, treatment, and follow-up data were collected prospectively. Frequency and associations of melanoma-related glaucoma at tumor diagnosis were assessed. Incidence of developing secondary glaucoma after diagnosis was estimated by Kaplan-Meier analysis. Independent risk factors were modeled using Cox regression. Melanoma-related glaucoma and related risk factors. Forty-five patients (5.8%; 95% confidence interval [CI], 4.2-7.6) had tumor-related secondary glaucoma at diagnosis, 34 (76%) from a narrow-to-closed angle (25 had direct angle invasion) and 10 (22%) from anterior neovascularization. Synchronous metastases were common in patients with initial secondary glaucoma (11% vs. 1.2% with incident glaucoma, P= 0.005). Patients with secondary glaucoma were often male (58% vs. 48% without glaucoma; P= 0.010) and had larger tumors (median thickness, 9.1 vs. 4.0 mm; P < 0.001) involving the ciliary body (43% vs. 21%; P < 0.001) with retinal detachment (53% vs. 30%; P < 0.001). One hundred and sixty-eight patients 165 of which were treated with brachytherapy developed incident tumor- or treatment-related secondary glaucoma a median of 1.7 years (range, 0.1-13.6) after tumor diagnosis. Cumulative proportion of developing secondary glaucoma was 23% (95% CI, 20-27) at 5 years. The most common mechanism was neovascularization in 119 patients (71%; 95% CI, 63-78). By multivariable regression, initial retinal detachment 3 to 4 quadrants (hazard ratio [HR], 2.18; P < 0.001), initial intraocular pressure 17 mmHg or higher (HR, 1.64; P= 0.01), and tumor thickness predicted incident secondary glaucoma. Secondary glaucoma at initial uveal melanoma diagnosis predicts high risk of synchronous metastases. Although anterior neovascularization is the most common mechanism for secondary glaucoma after diagnosis, other mechanisms such as angle narrowing and anterior chamber hemorrhage are not infrequent. Initial retinal detachment and intraocular pressure with tumor thickness could inform interim assessments of intraocular pressure and neovascularization.

Close spatial distance and direct gaze bring better communication outcomes and more intertwined neural networks

Non-verbal cues tone our communication. Previous studies found that non-verbal factors, such as spatial distance and gaze direction, significantly impact interpersonal communication. However, little is known about the behind multi-brain neural correlates and whether it could affect high-level creative group communication. Here, we provided a new, scalable, and neuro-based approach to explore the effects of non-verbal factors on different communication tasks, and revealed the underlying multi-brain neural correlates using fNIRS-based hyperscanning technique. Across two experiments, we found that closer spatial distance and more direct gaze angle could promote collaborative behaviors, improve both creative and non-creative communication outcomes, and enhance inter-brain neural synchronization. Moreover, compared to the non-creative communication task, participants’ inter-brain network was more intertwined when performing the creative communication task. These findings suggest that close spatial distance and direct gaze serve as positive social cues, bringing interacting brains into alignment and optimizing inter-brain information transfer, thus improving communication outcomes.

Low-temperature in situ CO2 enhanced oil recovery

The new generation in situ CO2 enhanced oil recovery (ICE), which delivers CO2 by injection of a CO2 generating agent solution, was proven to offer robust recovery performances and potential cost and workflow benefits. However, the developed ICE systems are either formulated with a complex fluid recipe or a simplified version of a fluid system limited by high-temperature requirements. This work focused on removing the requirement of high reservoir temperature in our previous work while maintaining the simplicity of the single fluid injection system. Urease is studied as the catalyst for urea hydrolysis and evaluated experimentally. The denaturation behavior of urease and the reaction kinetics of the catalyzed urea hydrolysis process are tested at different urea concentrations, urease concentrations, and temperatures. Four sets of one-dimensional sand pack flowthrough experiments are conducted to verify the tertiary recovery potential of the newly developed low-temperature ICE system with different lithology. The extent of wettability alteration and the recovery mechanism for different lithologies was determined through core sample imbibition experiments and direct contact angle measurements. From the experimental results, urease-catalyzed urea hydrolysis is proven to be effective in tertiary oil recovery applications below the 50 °C reservoir temperature range with urea conversion ratio up to 68.7 %. The selected low-temperature ICE system (10 wt% urea solution with 31 U/g urease) had superior tertiary recoveries(Etr) in the flowthrough test for sandstone(Etr = 31.3 %) and carbonate(Etr = 27.5 %) than the corresponding high-temperature cases. Imbibition tests of this improved formulation with various porous media show distinct wettability reversal trends towards a more water-wet state post imbibition. This trend is associated with the produced NH3 and CO2 due to urea hydrolysis. Both oil-aged sandstone and carbonate imbibition tests show noticeable water wetness improvement. The observations of this work significantly expand the operational envelopes of the current ICE system.

Direct slip angle control for rotor side converter of standalone DFIG‐DC system

This paper presents a direct slip angle control (DSAC) for rotor side power converter of standalone doubly-fed induction generator (DFIG) DC systems. The conventional direct torque control (DTC) for the rotor side converter (RSC) of the standalone DFIG-DC system is also introduced to evaluate the proposed DSAC compared to the conventional DTC method. In this regard, the proposed DSAC method is mathematically analyzed. Then, three states including output DC voltage change, wind speed change, and load change are simulated and performed for both the proposed DSAC and conventional DTC methods. Various simulations and experiments substantiate that the electromagnetic torque ripple, current harmonics, and the output DC voltage dip, caused by the sudden load-change, are reduced in the proposed DSAC method compared to the conventional DTC method. Besides, the parameter dependency is reduced in the proposed DSAC method since the stator voltage and current sensors are removed.