Independent Points Research Articles

Secure Transmissions in Millimeter Wave SWIPT UAV-Based Relay Networks

In this letter, we consider secure transmissions of millimeter wave simultaneous wireless information and power transfer unmanned aerial vehicle (UAV) relay networks, where a source transmits confidential information to an energy-constrained destination on the ground with the help of a UAV-based relay in the presence of multiple independent homogeneous Poisson point process eavesdroppers. First, we derive closed-form expression of the lower bound of average secrecy rate using 3-D antenna gain model. Then, we study the secrecy rate lower bound maximization problem by optimizing the source/UAV transmit power, power splitting ratio, and UAV’s location. To solve this non-convex problem, we propose an alternate optimization algorithm by solving three sub-problems iteratively. Simulation results show that the proposed algorithm can greatly improve the average secrecy rate.

Multi-Input Ćuk-Derived Buck-Boost Voltage Source Inverter for Photovoltaic Systems in Microgrid Applications

This paper presents a multi-input Ćuk-derived Buck-Boost voltage source inverter (CBBVSI) for Photovoltaic (PV) systems. The proposed topology consists of a single-stage DC-AC inverter that combines both DC-DC and DC-AC stages. The DC-DC stage is used for stepping-up the voltage from the PV generator. Simultaneously, the DC-AC stage is used for interfacing the PV source with the AC grid. The topology allows three sources to utilize the antiparallel diodes for each inverter leg for transferring the energy. The proposed system exhibits several features such as a reduction of the number of components compared to typical two-stage structures, and Split-Source Inverter (SSI), and Z-Source Inverter (ZSI) topologies. Moreover, the power of each PV source can be harvested either simultaneously or separately since independent Maximum Power Point Tracking (MPPT) is performed. The system was simulated using MATLAB/SIMULINK software and a 1 kW laboratory prototype was implemented to verify the operation of the proposed CBBVSI. The numerical simulations are presented together with the experimental results, showing a good agreement.

2500-Channel single-shot areal profilometer using hyperspectral interferometry with a pinhole array

Surface profilometry techniques such as coherent scanning interferometry or focus variation require long scan times and are thus vulnerable to environmental disturbance. Hyperspectral interferometry (HSI) overcomes the problem by recording all the spatial and spectral information necessary to reconstruct a 2D surface height map in a single shot. In this paper, we present a new HSI system that uses a pinhole array to provide the necessary gaps for the spectral information. It is capable of measuring 2500 independent points, twice the previous maximum number, with a maximum unambiguous depth range of ∼825 µm and a larger maximum surface tilt angle of 33.3 mrad. The use of phase information allows height to be measured to a precision of ∼6 nm, an order of magnitude improvement on previous HSI systems.

Uncertainty analysis of species distribution models.

The maximum entropy model, a commonly used species distribution model (SDM) normally combines observations of the species occurrence with environmental information to predict the geographic distributions of animal or plant species. However, it only produces point estimates for the probability of species existence. To understand the uncertainty of the point estimates, we analytically derived the variance of the outputs of the maximum entropy model from the variance of the input. We applied the analytic method to obtain the standard deviation of dengue importation probability and Aedes aegypti suitability. Dengue occurrence data and Aedes aegypti mosquito abundance data, combined with demographic and environmental data, were applied to obtain point estimates and the corresponding variance. To address the issue of not having the true distributions for comparison, we compared and contrasted the performance of the analytical expression with the bootstrap method and Poisson point process model which proved of equivalence of maximum entropy model with the assumption of independent point locations. Both Dengue importation probability and Aedes aegypti mosquito suitability examples show that the methods generate comparatively the same results and the analytic method we introduced is dramatically faster than the bootstrap method and directly apply to maximum entropy model.

Measuring the Two-Dimensional Temperature Profile of Carbon Fiber Reinforced Polymers During Drilling Using Distributed Fiber Sensing

The spatio-temporal evolution of the temperature induced over carbon fiber reinforced polymer (CFRP) laminates during drilling is monitored in real-time using a distributed optical fiber sensor based on optical frequency-domain reflectometry (OFDR). The proposed distributed measurement technique enables the simultaneous monitoring of thousands independent points on a CFRP plate during machining, being of special interest to measure the internal temperature of a workpiece. Experimental results validate the use of distributed OFDR-based sensing for this novel application, demonstrating a precise reconstruction of the two-dimensional (2D) temperature profile around the drilled hole, with a 2 mm spatial resolution and a sampling rate of 23.8 Hz (corresponding to a measurement interval of 42 ms). The high spatial and temporal resolutions provided by OFDR sensing offer unique features for this application, allowing for an accurate identification of the temporal evolution and spatial distribution of the 2D temperature profile originated during drilling. By embedding the sensing optical fiber in the interface between CFRP laminates and metals, a full map of the internal (interlayer) temperature of the CFRP plate can be obtained, demonstrating a feature that cannot be obtained by any other sensing technology. The proposed method can constitute a relevant tool for the identification of potential high temperatures occurring during machining, which could affect the quality of the borehole, induce material defects, and compromise the safety of an entire composite structure in service.

Stochastic Geometric Performance Analyses for the Cooperative NOMA With the Full-Duplex Energy Harvesting Relaying

In this paper, the cooperative non-orthogonal multiple access (C-NOMA) transmission with the full-duplex energy harvesting relaying (FDEHR) is investigated for enhancing the spectrum and energy efficiency. The exact outage probability is derived over Nakagami-$m$ frequency-selective fading channels. In addition, a novel near-far user pairing strategy is proposed in accordance with the geographic limitations, where the energy-harvesting-effective and successive-interference-cancelation-effective zones are demarcated according to power splitting factors, energy conversion coefficients, and power allocation parameters. The stochastic geometric model is also studied in which all users are distributed as an independent homogeneous Poisson point process. Then, the transmission probability of the C-NOMA conveyance with the FDEHR for a typical user is analyzed by utilizing the Markov chain model. Monte Carlo simulation is executed to verify the mathematical derivations. Both analytical and simulation results demonstrate that the near user possesses a lower outage probability than the far user does under the original NOMA transmission, whereas the outage performance of the far user could be improved so that he behaves better than the near user when the C-NOMA transmission with the FDEHR is applied.

MODEL OF A MATRIX CROSSCORRELATION FUNCTION OF THE PROBING AND REFLECTED VECTOR SIGNALS FOR A CONCEPTUAL DESIGN OF A SYNTHETIC APERTURE RADAR ON AN AERIAL CARRIER

In order to simulate the process of design development in full on computer models, including virtual tests of the synthetic aperture radar on an air carrier in model media, the study develops a structural scheme of the conceptual design of the synthetic aperture radar on an air carrier. The scheme is invariant with respect to the type of an air carrier with a synthetic aperture radar: an aircraft, a helicopter, an unmanned aerial vehicle and similar ones: an air carrier "enters" it by only an automatic control system, a model of trajectory instabilities and a spectrum of frequencies of elastic oscillations of its design. To perform a computer simulation of radar systems with full polarization sensing, a model of a matrix cross-correlation function of probing and reflected vector signals is proposed. As a model of the scattering object, a set of independent point reflectors distributed over space and generally having different rates of motion is accepted. The reflected signal is a sum of elementary signals, their form completely repeats the shape of the emitted signal, and the amplitude, the phase and polarization are respectively determined by the coordinate, velocity and polarization parameters of elementary reflectors forming a spatially extended object. Taking into account the developed models for the formation of the vector sounding signal and the matrix response function of the distributed radar object, a block-diagram of the model of the matrix cross-correlation function of the emitted and reflected vector signals is proposed. A block-diagram is the basis for the development of an algorithm and a program for computer modeling of the primary signal processing in a radar station with full polarization sensing.

Benchmarking study of the forces and centre of pressure derived from a novel smart-insole against an existing pressure measuring insole and force plate

This study identified a novel method of validating the force and Centre of Pressure (COP) obtained from pressure-measuring insoles, utilizing commercially available equipment. The focus of this research was to compare force and COP data between a newly developed Smart Insole (SI) and the Pedar (PE) insole using an independent point of reference device – the Kistler force plate (FP). Results showed good correlation between forces measured from both systems and the FP (R2 > 0.98) with RMSE of 11.2% and 5.6% respectively. For the COP, the Systematic Error (SE), k, and R2, are presented. For the SI, the COPx and COPy data achieved k = 0.763 and 1.009 (R2 = 0.855 and 0.990). For the PE, k = 0.155 and 1.0143 (R2 = 0.014 and 0.995). The SI is comparable to PE in terms of accuracy when measuring force and COP, with the advantages of being accurate, portable and cheaper.

Effects of Uncertainties in the Launch Parameters on the Pressure-Equalizing Air Film Around a Vertically Launched Underwater Vehicle

Many uncertain factors in the water-emerging process of a vehicle influence the taking effect of the air film around its shoulder in the load reduction and attitude control. Assuming the launch parameters (launch depth, vehicle velocity, and chamber pressure) as sources of uncertainties, the uncertain evolution process of the air film in the water-emerging process of a vehicle is quantified by adopting the nonintrusive polynomial chaos (NIPC) method with the sample space constructed using linearly independent probabilistic collocation points. A sensitivity analysis was conducted for the key performance indicators of the air film to evaluate the contribution of each uncertain launch parameter.

Comparing D-bar and common regularization-based methods for electrical impedance tomography

Objective: To compare D-bar difference reconstruction with regularized linear reconstruction in electrical impedance tomography. Approach: A standard regularized linear approach using a Laplacian penalty and the GREIT method for comparison to the D-bar difference images. Simulated data was generated using a circular phantom with small objects, as well as a ‘Pac-Man’ shaped conductivity target. An L-curve method was used for parameter selection in both D-bar and the regularized methods. Main results: We found that the D-bar method had a more position independent point spread function, was less sensitive to errors in electrode position and behaved differently with respect to additive noise than the regularized methods. Significance: The results allow a novel pathway between traditional and D-bar algorithm comparison.

Avelumab plus Axitinib versus Sunitinib for Advanced Renal-Cell Carcinoma

BackgroundIn a single-group, phase 1b trial, avelumab plus axitinib resulted in objective responses in patients with advanced renal-cell carcinoma. This phase 3 trial involving previously untreated patients with advanced renal-cell carcinoma compared avelumab plus axitinib with the standard-of-care sunitinib.MethodsWe randomly assigned patients in a 1:1 ratio to receive avelumab (10 mg per kilogram of body weight) intravenously every 2 weeks plus axitinib (5 mg) orally twice daily or sunitinib (50 mg) orally once daily for 4 weeks (6-week cycle). The two independent primary end points were progression-free survival and overall survival among patients with programmed death ligand 1 (PD-L1)–positive tumors. A key secondary end point was progression-free survival in the overall population; other end points included objective response and safety.ResultsA total of 886 patients were assigned to receive avelumab plus axitinib (442 patients) or sunitinib (444 patients). Among the 560 patients with PD-L1–positive tumors (63.2%), the median progression-free survival was 13.8 months with avelumab plus axitinib, as compared with 7.2 months with sunitinib (hazard ratio for disease progression or death, 0.61; 95% confidence interval [CI], 0.47 to 0.79; P<0.001); in the overall population, the median progression-free survival was 13.8 months, as compared with 8.4 months (hazard ratio, 0.69; 95% CI, 0.56 to 0.84; P<0.001). Among the patients with PD-L1–positive tumors, the objective response rate was 55.2% with avelumab plus axitinib and 25.5% with sunitinib; at a median follow-up for overall survival of 11.6 months and 10.7 months in the two groups, 37 patients and 44 patients had died, respectively. Adverse events during treatment occurred in 99.5% of patients in the avelumab-plus-axitinib group and in 99.3% of patients in the sunitinib group; these events were grade 3 or higher in 71.2% and 71.5% of the patients in the respective groups.ConclusionsProgression-free survival was significantly longer with avelumab plus axitinib than with sunitinib among patients who received these agents as first-line treatment for advanced renal-cell carcinoma. (Funded by Pfizer and Merck [Darmstadt, Germany]; JAVELIN Renal 101 ClinicalTrials.gov number, NCT02684006.)

Multi-Operator Cooperation for Green Cellular Networks With Spatially Separated Base Stations Under Dynamic User Associations

This paper presents a cooperation framework for sharing base stations (BSs) among ${N}$ number of collocated radio-access networks (RANs) for improving energy efficiency (EE). The proposed framework is equally applicable for collocated and non-collocated BSs belonging to multiple RANs. To the best of our knowledge, this paper is the first for developing such cooperation mechanisms among the spatially separated BSs of ${N}$ RANs. Independent hard-core Poisson point process (PPP) is used for modeling the locations of BSs with a minimal inter-BS distance, while locations of user equipment devices (UEs) are modeled using PPP. The proposed cooperation mechanisms enable the networks to serve UEs of other RANs allowing some BSs to switch into sleep mode for better EE. Call continuity, signal quality and call blocking limits are guaranteed during this dynamic BS switching. For avoiding high complexity of the generalized EE optimization problem, heuristically guided algorithms with different dynamic UE association policies are proposed. Network performance including fairness of the proposed cooperation under a wide range of system settings is thoroughly investigated. Simulation results clearly demonstrate a substantial improvement in EE as well as an extremely fair cooperation. Comparisons with the other works further validate the proposed framework.

Dual-Input Grid-Connected Photovoltaic Inverter With Two Integrated DC–DC Converters and Reduced Conversion Stages

A dual-input dual-buck inverter (DI-DBI) with integrated boost converters (IBCs) is proposed for grid-connected applications. The proposed DI-DBI is composed of two buck-type inverter-legs and two IBCs. Two renewable dc sources, with independent maximum power point tracking, can be realized with the DI-DBI. The IBCs are used to provide a constant and stable dc-bus voltage for the inverter-legs, enabling the inverter to operate well, even when the dc source voltage varies widely and is lower than the peak amplitude of the grid voltage. Unlike a conventional two-stage dc–ac inverter, only a small ratio of the input power needs to be processed by the IBCs. The other part of the input power is directly fed to the grid through the inverter-legs; therefore, in comparison with a conventional dc–dc converter and inverter cascaded two-stage solution, the conversion stages of the DI-DBI, power rating, and losses of the IBCs are all reduced. The switching loss can be reduced as well because of the multivoltage-level characteristics of the proposed DI-DBI. As a result, a higher efficiency is achieved. Modulation and control strategies are proposed to realize independent regulation of the two dc inputs. Operation principles and characteristics of the proposed DI-DBI are analyzed in detail. Experimental results have been provided to verify the effectiveness and advantages of the proposed method.

Dual-Input Single-Resonant Tank LLC Converter with Phase Shift Control for PV Applications

This paper proposes a dual-input LLC resonant converter that interfaces with two photovoltaic (PV) panels. The topology is a dual half-bridge LLC circuit with four active switches. This topology allows the two sources to share the same resonant tank for transferring energy to the load without the need for additional circuit components. A phase-shift pulsewidth modulation (PWM) control is employed to implement independent maximum power point tracking (MPPT) for each PV panel. Independent MPPT is achieved by varying the PWM phase shift of each source. Zero-voltage-switching is realized in all switches over the entire range of source voltage and load conditions. In addition, voltage stress across switches does not exceed the input PV voltage. A 500-W prototype was built to demonstrate the performance of the proposed topology. The input voltage range was selected between 25 and 50 V with an output voltage regulated at 220 V dc. Experimental results show that the proposed converter can achieve the peak efficiency of 95.8% while maintaining a wide input voltage range and implementing MPPT for each PV panel.

Anniversary Sylvets of Yuriy Stefanyk “Ulas Samchuk – his seventy years anniver- sary”and the memoir research “The Wise man “on a horse-raven”

The purpose of the work: to determine the place of Y. Stefanyk’s scientific work in Ukrainian literary criticism, to find out the value of his contribution to understanding the literary process in Ukraine in the twentieth century, to summarize scientific research of the life and workof the Ukrainian diaspora writer Ulas Samchuk. Research methods. We practice comparative-historical, biographical, descriptive, aestheticfunctional, comparative-typological methods, analysis and synthesis method, induction and deduction method, method of collecting, selecting and generalizing information data method in the given article. The scientific novelty of the study is to demonstrate a new, independent point of view of the work of the writer of the Ukrainian diaspora Ulas Samchuk; its presentating, analysis and study through the prism of Yuriy Stefanyk's literary study. Conclusions. Yuriy Stefanyk articles and essays examination on the study of the writers of the Ukrainian diaspora, namely: “Ulas Samchuk. Ulas Samchuk – his seventy years anniversary”, “Wise man “on a horse-raven”; convinces that the critic subtly feels the inherent features of each artist own style, draws attention to the aesthetic value of a particular author. He has a good feel for the colors of the language, especially the poetics of the writings of the writers he writes about. The literary school, acquired even with his father, and later in the publications with which he collaborated, the experience of research and textual work, and first of all, the literary talent led to the professionalism of his judgments, the credibility of assessments of aesthetic phenomena. We discovered the fate of the Ukrainian writer who was deprived of the right to create in Ukraine and for the Ukrainian people, but he found the conditions for creativity, the power for creation, and all this gradually returns, enriches our spiritual and cultural treasury, makes it eternal and immortal. Y. Stefanyk is a reprentative of a whole galaxy of creators-memoirists, such as Mykola Bazhansky, Yuriy Smo- lych and others. Y. Stefanyk’s research may be rarity in the study of the work of the writers of the Ukrainian diaspora.

Comparison of shaping ability of ProTaper Next and 2Shape nickel—titanium files in simulated severe curved canals

Aim: To evaluate the centering ability of ProTaper Next (PTN) and 2Shape (TS) nickel—titanium (NiTi) instruments in terms of maintaining the original root canal configuration in a simulated tooth with severe curvature. Methodology: Twenty standardized simulated curved root canals were prepared to an apical size of 0.25 mm using PTN and TS (n = 10 canal/group) nickel-titanium files. A gig was constructed to enable reproducible image acquisition using a photographic camera. Pre- and post-instrumented images were recorded and superimposed using a computer software. The ability of the instruments to remain centered in the canal was determined by calculating a centering ratio at three independent points of the simulated canal: coronal, middle and apical third of the curvature, using a computer software. Statistical analysis was performed using one-way analysis of variance (ANOVA) followed by independent sample t-test at 5% significance level. Results: No significant difference was found between the two systems (p &gt; 0.05). At the apical third, the mean centering ratio was significantly higher than the centering ratio of the coronal and the middle thirds in both TS and PTN (p &lt; 0.05). Conclusions: There were no significant differences in the centering ability of the ProTaper Next and 2Shape systems in simulated severe curved canals. Both systems exhibited some degree of transportation, especially in the apical third.

The isotropic constant of random polytopes with vertices on convex surfaces

For an isotropic convex body K⊂Rn we consider the isotropic constant LKN of the symmetric random polytope KN generated by N independent random points which are distributed according to the cone probability measure on the boundary of K. We show that with overwhelming probability LKN≤Clog(2N∕n), where C∈(0,∞) is an absolute constant. If K is unconditional we argue that even LKN≤C with overwhelming probability and thereby verify the hyperplane conjecture for this model. The proofs are based on concentration inequalities for sums of sub-exponential or sub-Gaussian random variables, respectively, and, in the unconditional case, on a new ψ2-estimate for linear functionals with respect to the cone measure in the spirit of Bobkov and Nazarov, which might be of independent interest.

Classification of empty lattice 4-simplices of width larger than two

A lattice d d -simplex is the convex hull of d + 1 d+1 affinely independent integer points in R d {\mathbb R}^d . It is called empty if it contains no lattice point apart from its d + 1 d+1 vertices. The classification of empty 3 3 -simplices has been known since 1964 (White), based on the fact that they all have width one. But for dimension 4 4 no complete classification is known. Haase and Ziegler (2000) enumerated all empty 4 4 -simplices up to determinant 1000 and based on their results conjectured that after determinant 179 179 all empty 4 4 -simplices have width one or two. We prove this conjecture as follows: - We show that no empty 4 4 -simplex of width three or more can have a determinant greater than 5058, by combining the recent classification of hollow 3-polytopes (Averkov, Krümpelmann and Weltge, 2017) with general methods from the geometry of numbers. - We continue the computations of Haase and Ziegler up to determinant 7600, and find that no new 4 4 -simplices of width larger than two arise. In particular, we give the whole list of empty 4 4 -simplices of width larger than two, which is as computed by Haase and Ziegler: There is a single empty 4 4 -simplex of width four (of determinant 101), and 178 empty 4 4 -simplices of width three, with determinants ranging from 41 to 179.

Meta-Analytic Evidence of the Criterion Validity of Gordon’s Music Aptitude Tests in Published Music Education Research

This meta-analytic study examined the validity of Gordon’s music aptitude tests as predictors of other musical variables. The four tests analyzed were the Music Aptitude Profile (1965), Primary Measures of Music Audiation (1979), Intermediate Measures of Music Audiation (1982), and Advanced Measures of Music Audiation (1989). Separate analyses were performed for tonal, rhythm, and composite constructs of music aptitude. From 47 music education journal articles that met requirements for inclusion, 215 independent data points representing 6,086 participants were collapsed into an overriding set of five criterion categories: (a) aural perception, (b) achievement, (c) creativity, (d) affective outcomes, and (e) musical engagement. Moderators potentially affecting validity included audiation type, sampling method, grade level, criterion test type, and year of publication. Results revealed estimated true criterion-related validities of .45 (tonal), .46 (rhythm), and .53 (composite). Gordon’s music aptitude tests were consistently but not always strongly associated with many desirable musical outcomes. Analysis of correlations by subtest and criterion category produced mixed results, and high levels of between-study heterogeneity could not be explained through meta-regression moderator analysis.

Grid-Connected Wind-Solar Cogeneration Using Back-to-Back Voltage-Source Converters

This paper introduces a new topology, yet simple and efficient, for a grid-connected wind-solar cogeneration system. A permanent magnet synchronous generator-based full-scale wind turbine is interconnected to the utility-grid via back-to-back voltage-source converters (VSCs). The dc-link capacitor has been utilized to directly interface a photovoltaic solar generator. No dc/dc conversion stages are required, and hence, the hybrid system is simple and efficient. Moreover, the proposed topology features an independent maximum power point tracking for both the wind and the solar generators to maximize the extraction of the renewable energy. The regulation of the VSCs is achieved via the vector control in the rotating reference frame. The detailed small-signal models for the system components are developed to characterize the overall stability. The influence of the utility-grid faults on the performance of the proposed system is also investigated. Nonlinear time-domain simulation results under different operating conditions are presented to validate the effectiveness of the proposed topology.