Independent Points Research Articles

Parametric investigation of the phase characteristics of a beta-type free piston Stirling engine based on a thermodynamic-dynamic coupled model

In this study, to reveal the phase characteristics of a beta-type free piston Stirling engine (β-FPSE), a thermodynamic-dynamic coupled model is proposed and verified experimentally. With the phasor notation method, the influences of the heating temperature, cooling temperature, spring stiffness and damping coefficients on the phases of displacer and power piston, and the output performance are investigated. The results indicate that the phase angles of the displacer and power piston increase with the heating temperature, and decrease with the cooling temperature. In the variation of power piston phase with its spring stiffness, a point of temperature independence (PTI) is identified. In the variation in the power piston phase with the displacer damping coefficient, a point of damping balance (PDB) is identified. A hysteresis of the PDB will occur if the heating temperature increases. In addition, the output power and power angle are obtained at the same damping coefficient of the displacer, which is equal to the displacer damping coefficient at the PDB if the spring stiffness ratio is less than 3.31. Moreover, based on the PV diagrams of different spring stiffness and damping coefficients, the compression ratio and pressure ratio for the optimum output power and efficiency are determined, respectively.

A New Method for Positional Accuracy Analysis in Georeferenced Satellite Images without Independent Ground Control Points

This paper introduces a new method to analyze the positional accuracy of georeferenced satellite images without the use of ground control points. Compared to the traditional method used to carry out this kind of analysis, our approach provides a semiautomatic way to obtain a larger number of control points that satisfy the requirements of current standards regarding the size of the set of sample points, the positional accuracy of such points, the distance between points, and the distribution of points in the sample. Our methodology exploits high quality orthoimages, such as those provided by the Aerial Orthography National Plan (PNOA)—developed by the Spanish National Geographic Institute—and has been tested on spatial data from Landsat 8. Our method works under the current international standard (ASPRS 2014) and exhibits similar performance than other well-known methods to analyze the positional accuracy of georeferenced images based on the use of independent ground control points. More specifically, the positional accuracy achieved for a Landsat 8 dataset evaluated by the traditional method is 5.22 ± 1.95 m, and when evaluated with the proposed method, it exhibits a typical accuracy of 5.76 ± 0.50 m. Our experimental results confirm that the method is equally effective and less expensive than other available methods to analyze the positional accuracy of satellite images.

Radio Resource Dimensioning for Low Delay Access in Licensed OFDMA IoT Networks.

In this paper, we focus on the radio resource planning in the uplink of licensed Orthogonal Frequency Division Multiple Access (OFDMA) based Internet of Things (IoT) networks. The average behavior of the network is considered by assuming that active sensors and collectors are distributed according to independent random Poisson Point Process (PPP) marked by channel randomness. Our objective is to statistically determine the optimal total number of Radio Resources (RRs) required for a typical cell. On one hand, the allocated bandwidth should be sufficiently large to support the traffic of the devices and to guarantee a low access delay. On the other hand, the over-dimensioning is costly from an operator point of view and induces spectrum wastage. For this sake, we propose statistical tools derived from stochastic geometry to evaluate, adjust and adapt the allocated bandwidth according to the network parameters, namely the required Quality of Service (QoS) in terms of rate and access delay, the density of the active sensors, the collector intensities, the antenna configurations and the transmission modes. The optimal total number of RRs required for a typical cell is then calculated by jointly considering the constraints of low access delay, limited power per RR, target data rate and network outage probability. Different types of networks are considered including Single Input Single Output (SISO) systems, Single Input Multiple Output (SIMO) systems using antenna selection or Maximum Ratio Combiner (MRC), and Multiuser Multiple Input Multiple Output (MU-MIMO) systems using Zero-Forcing decoder.

RCS Feature Extraction Using Discretized Point Scatterer With Compressive Sensing

This letter presents a novel technique for radar cross section (RCS) feature extraction using discrete scattering center modeling and a basis pursuit denoising (BPDN) algorithm for compressive sensing. From the Stratton–Chu formula, a high-frequency assumption has been applied to define the target object as a combination of independent point scatterers. Using the BPDN solver, complex-valued scattering sources are determined from a matrix equation for the scattering problem. Using a numerical example, it has been verified that the proposed method can extract the RCS feature accurately, and the measurement efficiency is much higher compared to that of conventional methods.

ASSESSMENT OF THE ACCURACY AND PRECISION OF MyRTKnet REAL-TIME SERVICES

From a network of ninety-six (96) Continuously Operating Reference Stations (CORS), the Department of Survey and Mapping Malaysia (DSMM) has developed a reliable real-time data streaming service known as the Malaysia Real-Time Kinematic GNSS Network (MyRTKnet). MyRTKnet is now operating on Leica SpiderNet system that is configured to provide coordinate to users in Geocentric Datum of Malaysia 2000 (GDM2000). As the name implied, GDM2000 is a geocentric datum for Malaysia, developed based upon the International Terrestrial Reference Frame (ITRF) 2000 or ITRF2000. One could argue that the quality of coordinates provided by MyRTKnet are less optimal as the latest realisation of ITRF at present is ITRF2014. This study aims to investigate the accuracy and precision of the resultant coordinates from MyRTKnet real-time services through a comparison with the control-quality coordinates from a network of post-processed data at some independent points for positioning purpose. Meanwhile for mapping purpose, the coordinates from Network Real-Time Kinematic (NRTK) at selected Cadastral Reference Marks (CRM) points were compared with their known values. The results show that the observed points in ITRF2000 move approximately 37 cm away from the points in ITRF2014 due to the constant movement of Sundaland Block. Meanwhile for the assessment of NRTK technique, there is no significant displacement for coordinates in ITRF2000 but ITRF2014 with the values of 4.4 and 39.8 cm at KDOJ point, respectively. The discrepancy in ITRF2014 could be due to the improper datum transformation procedure.

Automotive Velocity Sensing Using Millimeter-Wave Interferometric Radar

In this article, we demonstrate the use of interferometric radar for high-accuracy measurement of the ground speed of a moving vehicle. Recent work has shown the capability of radar systems using interferometric antenna apertures to directly measure the angular velocity of objects. In this work, we apply this new measurement to the automotive application of velocity estimation. We start by formulating the interferometric response from a ground surface, which is modeled as a summation of independent point scatterers. Next, we present two velocity estimation methods: a Bayesian method that uses a signal model and a neural network-based approach. We then describe a 40-GHz interferometric radar system that we have developed and present on-vehicle measurements. Finally, we present the results of the two estimators and compare these results with the theoretical accuracy of the system. We show that the Bayesian and neural net estimators achieved a root-mean-square velocity error of 0.403 and 0.183 m/s, respectively.

A Multiport Modular DC–DC Converter With Low-Loss Series LC Power Balancing Unit for MVDC Interface of Distributed Photovoltaics

An input-independent and output-series modular dc-dc converter with multiple input ports and high voltage conversion ratio can apply well to medium-voltage dc interface of distributed photovoltaics (PV). However, PV power mismatch will result in output voltage imbalance of the submodules (SMs), which is contrary to the standardized multimodule design. In this article, a multiport modular dc-dc converter with low-loss series LC power balancing unit (PBU) is proposed to address this problem. An isolated dc-dc converter is employed as the SM, which consists of full-bridge (FB) circuit on the PV side and half-bridge (HB) circuit on the grid side. Independent maximum power point tracking can be realized by controlling the phase shift between the FB and the HB, while voltage balancing (or power balancing) of SMs can be achieved by regulating the phase shift between adjacent HBs. Only one inductor and one capacitor are used in the PBU and all the switches of SM turn on with zero-voltage switching, which contributes to the low-cost and low-loss characteristic of the converter. Simulations and experiments are carried out to verify the validity of the theory.

Assessment of the maxilla‐mandible‐nasion angle in normal and aneuploid foetuses in the first trimester of pregnancy

This retrospective study aims to determine whether the maxilla-mandible-nasion (MMN) angle can be reliably measured in the first trimester, to describe normal ranges, and to determine if significant changes occur in foetuses with aneuploidies. The MMN angle was measured in stored 2D-ultrasound images of 200 normal fetal profiles between 11+0 and 13+6 weeks of gestation. Each image was analyzed by two observers at two independent time points. Bland-Altmann analysis was performed to evaluate the reliability of the measurements. Additionally, the MMN angle was measured on sonograms from 140 aneuploid foetuses. The mean MMN angle in normal foetuses from 11 to 14 weeks of gestation was 15.4°. Reliability of the measurement was high when repeatedly measured by the same observer (ICC = 0.92 and 0.82) and between two observers (ICC = 0.77 and 0.63). Average MMN values in foetuses with trisomy 21, 13, and Turner syndrome were significantly higher than those measured in normal foetuses. The highest differences were observed in foetuses with trisomy 13. Among those, 62% had an MMN angle above the 95th percentile and 92% above the normal mean. The MMN angle can be reliably measured in early pregnancy and is abnormal in about 60% of foetuses with trisomy 13.

Statistical analysis of some correlations between compression index and Atterberg limits

The relationship between the compression index and Atterberg limits (liquid limit, plastic limit, shrinkage limit) is well-known. Several equations are found in literature for general correlations or more specifically for correlations considering the state of the soil (e.g. remolded or undisturbed). This paper evaluates different studies considering 250 data points, and relations among the compression index and the liquid limit, index of plasticity, index of shrinkage, soil activity and plasticity ratio are provided. These relations are validated against 12 independent data points. The objective of the research is not to provide a new relation, but it is rather to statistically evaluate the input data used to obtain the new relationships. Therefore, several statistical analyses considering the root mean square error (RMSE), a probabilistic analysis, ranking distance ( $$\mathrm{RD}$$ ) and ranking index ( $$\mathrm{RI}$$ ) are performed by taking into account the correlations obtained to quantify the accuracy of each correlation. A Monte Carlo simulation with 100,000 simulations showed that the type of correlation has an influence on the distribution output.

Condensation of Rodlike Counterions on a Charged Cylinder

We study the condensations of dumbbell-like counterions onto an oppositely charged cylinder at weak and strong electrostatic coupling strengths. Performing extensive Monte Carlo simulations, we show that the condensation characteristics of the dumbbell ions can be understood by viewing dumbbell ions of length d as point ions with an effective valency depending on the radial distance r from the cylinder’s axis. In terms of the condensation behavior, dumbbell ions behave as two independent point ions if r ≪ d, but act as a single point ion with twofold valency when r ≫ d. Such a distance-dependent effective valency as a characteristic of ions of extended structures explains a unique feature in the condensed counterion fraction and heat capacity at both weak and strong coupling strengths.

Distribution of the Distance Between Two Random Points in a Body from $$\boldsymbol{R}^{\boldsymbol{n}}$$

In the present paper a formula for calculation of the density function $$f_{\rho}(x)$$ of the distance between two independent points randomly and uniformly chosen in a bounded convex body $$D$$ is given. The formula permits to find an explicit form of density function $$f_{\rho}(x)$$ for body with known chord length distributions. In particular, we obtain an explicit expression for $$f_{\rho}(x)$$ in the case of a ball of diameter $$d$$ . A simulation model is suggested to calculate empirically the cumulative distribution function of the distance between two points in a body from $$R^{n}$$ , where explicit form of the function is hard to obtain. In particular, simulation is performed for balls and ellipsoids in $$R^{n}$$ .

Analysis of antibiotic treatment of children in a Shanghai tertiary hospital based on point prevalence surveys

BackgroundMisuse and overuse of antibiotics by physicians in the treatment of children is common in China. This study aimed to reveal the overall use of antibiotics to treat children hospitalized in four types of pediatric wards.MethodsSeven independent point prevalence surveys (PPSs) were conducted in Shanghai Children’s Hospital of Shanghai Jiao Tong University over the period 2012 to 2018. Pediatric ward types were defined general pediatric medical, pediatric surgical, pediatric intensive care units (PICU), and neonatal.ResultsA total of 3975 pediatric patients were included in the study, of which 63.9% received at least one dose antibiotic. The top five classes of antibiotics administered were cephalosporins (43.8%, n = 1743), penicillins (13.2%, n = 526), carbapenems (8.7%, n = 347), nitroimidazoles (7.1%, n = 281) and macrolides (6.5%, n = 257). The five most commonly used generic antibiotics were cefuroxime (14.9%, n = 594), ceftriaxone (9.7%, n = 387), cefotaxime (9.0%, n = 358), meropenem (8.1%, n = 320) and ampicillin/sulbactam (6.0%, n = 239). Meropenem was among top five antibiotics prescribed in the general pediatric, PICU and neonatal wards and sixth in the pediatric surgical wards. Of all children on antibiotics, 23.4% received prophylactic treatment, and prophylaxis accounted for 68.1% of indications for treatment in the pediatric surgical wards.ConclusionsGiven that over-treatment with third-generation cephalosporins and carbapenems has been associated with treatment-resistant infections, the prescription of these drugs should be strictly controlled and monitored, and measures should be taken to improve the management of surgical prophylaxis in hospitalized children in China.

Multi-Objective Modeling of Leading-Edge Serrations Applied to Low-Pressure Axial Fans

Abstract A novel modeling strategy is proposed which allows high-accuracy predictions of aerodynamic and aeroacoustic target values for a low-pressure axial fan, equipped with serrated leading edges. Inspired by machine learning processes, the sampling of the experimental space is realized by use of a Latin hypercube design plus a factorial design, providing highly diverse information on the analyzed system. The effects of four influencing parameters (IP) are tested, characterizing the inflow conditions as well as the serration geometry. A total of 65 target values in the time and frequency domains are defined and can be approximated with high accuracy by individual artificial neural networks. Furthermore, the validation of the model against fully independent test points within the experimental space yields a remarkable fit, even for the spectral distribution in 1/3-octave bands, proving the ability of the model to generalize. A metaheuristic multi-objective optimization approach provides two-dimensional Pareto optimal solutions for selected pairs of target values. This is particularly important for reconciling opposing trends, such as the noise reduction capability and aerodynamic performance. The chosen optimization strategy also allows for a customized design of serrated leading edges, tailored to the specific operating conditions of the axial fan.

Сurrent issues of the Church: Catholic and Orthodox view

Modern processes — economic, political, and social, taking place in the world affect the Church as an institution and believers of different confessions. Looking at these problems from the independent points of view of Orthodoxy and Catholicism is interesting and informative, pointing out the similarity in some issues and the important difference in others.

Methodology of Processing Single-Strip Blocks of Imagery with Reduction and Optimization Number of Ground Control Points in UAV Photogrammetry

Unmanned aerial vehicle (UAV) systems are often used to collect high-resolution imagery. Data obtained from UAVs are now widely used for both military and civilian purposes. This article discusses the issues related to the use of UAVs for the imaging of restricted areas. Two methods of developing single-strip blocks with the optimal number of ground control points are presented. The proposed methodology is based on a modified linear regression model and an empirically modified Levenberg–Marquardt–Powell algorithm. The effectiveness of the proposed methods of adjusting a single-strip block were verified based on several test sets. For method I, the mean square errors (RMSE) values for the X, Y, Z coordinates of the control points were within the range of 0.03–0.13 m/0.08–0.09 m, and for the second method, 0.03–0.04 m/0.06–0.07 m. For independent control points, the RMSE values were 0.07–0.12 m/0.06–0.07 m for the first method and 0.07–0.12 m/0.07–0.09 m for the second method. The results of the single-strip block adjustment showed that the use of the modified Levenberg–Marquardt–Powell method improved the adjustment accuracy by 13% and 16%, respectively.

Complexity in psychological self-ratings: implications for research and practice

BackgroundPsychopathology research is changing focus from group-based “disease models” to a personalized approach inspired by complex systems theories. This approach, which has already produced novel and valuable insights into the complex nature of psychopathology, often relies on repeated self-ratings of individual patients. So far, it has been unknown whether such self-ratings, the presumed observables of the individual patient as a complex system, actually display complex dynamics. We examine this basic assumption of a complex systems approach to psychopathology by testing repeated self-ratings for three markers of complexity: memory, the presence of (time-varying) short- and long-range temporal correlations; regime shifts, transitions between different dynamic regimes; and sensitive dependence on initial conditions, also known as the “butterfly effect,” the divergence of initially similar trajectories.MethodsWe analyzed repeated self-ratings (1476 time points) from a single patient for the three markers of complexity using Bartels rank test, (partial) autocorrelation functions, time-varying autoregression, a non-stationarity test, change point analysis, and the Sugihara-May algorithm.ResultsSelf-ratings concerning psychological states (e.g., the item “I feel down”) exhibited all complexity markers: time-varying short- and long-term memory, multiple regime shifts, and sensitive dependence on initial conditions. Unexpectedly, self-ratings concerning physical sensations (e.g., the item “I am hungry”) exhibited less complex dynamics and their behavior was more similar to random variables.ConclusionsPsychological self-ratings display complex dynamics. The presence of complexity in repeated self-ratings means that we have to acknowledge that (1) repeated self-ratings yield a complex pattern of data and not a set of (nearly) independent data points, (2) humans are “moving targets” whose self-ratings display non-stationary change processes including regime shifts, and (3) long-term prediction of individual trajectories may be fundamentally impossible. These findings point to a limitation of popular statistical time series models whose assumptions are violated by the presence of these complexity markers. We conclude that a complex systems approach to mental health should appreciate complexity as a fundamental aspect of psychopathology research by adopting the models and methods of complexity science. Promising first steps in this direction, such as research on real-time process monitoring, short-term prediction, and just-in-time interventions, are discussed.

Single-Phase Current Source Inverter with Reduced Ground Leakage Current for Photovoltaic Applications

Integrated power electronics for photovoltaic applications has attracted increasing interest, due to the possibility of having grid-connected photovoltaic modules with independent maximum power point tracking and high reliability. In this paper, a single-phase Current Source Inverter (CSI) is discussed for a photovoltaic application. The basic CSI topology will be explained for the sake of completeness, highlighting its main features and analyzing the ground leakage current problem, an important benchmark for photovoltaic application. A novel topology, called CSI5, is proposed in this work. The main feature is the presence of additional switches for ground leakage current reduction. The performance of the proposed topology is assessed by numerical simulation, and the experimental results confirm that this solution is able to strongly reduce the ground leakage current and conduction power losses.

Division Method of Pollutant Discharge Region and Estimation of the Mainland-Based Pollutant Loads Entering the Bohai Sea

Ding, D.-s.; Li, K.-q.; Su, Y.; Liang, S.-k.; Qu, K.-m.; Cui, Z.-g.; Zhang, P., and Wang, X.-l., 2020. Division method of pollutant discharge region and estimation of the mainland-based pollutant loads entering the Bohai Sea. In: Yang, D.F. and Wang, H. (eds.), Recent Advances in Marine Geology and Environmental Oceanography. Journal of Coastal Research, Special Issue No. 108, pp. 312–316. Coconut Creek (Florida), ISSN 0749-0208.The land-based pollutant total load control (PTLC) is an effective approach to comprehensively solve the current problem of marine pollution. The pollutant discharge region (PDR), which is the responsibility and source group, was divided for PTLC source assessment. According to the U.S. TMDLs mode, by tracing the source of the 145 points from which the land-based pollutants were discharged into the Bohai Sea, the Bohai rim was divided into two parts: the Bohai pollutant discharge band (in-band for short), whose pollutant was discharged into the Bohai Sea, and out-of-band, whose pollutant was not discharged into the Bohai Sea. The in-band area included 343 county-level administrative regions of 37 prefectural-level cities. The PDRs are further formed by the intersection of 115 watersheds, 13 sewage plants, and 17 national key monitoring sewage enterprises. These sewage enterprises discharged sewage into the sea by using an independent point, with 343 county-level administrative regions of 37 prefectural-level cities in-band. A total of 145 PDRs was combined to 42 and were further lumped together into three PDR systems. On the basis of the PDRs, the area, CODCr, nitrogen (DIN), and phosphorus (DTP) discharge flux of each PDR were estimated, which totaled 40,4476 km2, 941,072 tons, 90,570 tons, and 12,808.8 tons, respectively. The CODCr, DIN, and DTP load per one square kilometer of each PDR were estimated, which averaged 4.99, 0.42, and 0.09 tons, respectively, and varied between 0.001 and 64.068, 0.006 and 5.063, and 0.0007 and 1.672, respectively. The key PDRs were discussed. From the results, it is seen that the key PDRs mainly lie in Hebei Province along with the large rivers.

Cox Models for Vehicular Networks: SIR Performance and Equivalence

We introduce a general framework for the modeling and analysis of vehicular networks by defining street systems as random 1D subsets of $\mathbb{R}^{2}$. The street system, in turn, specifies the random intensity measure of a Cox process of vehicles, i.e., vehicles form independent 1D Poisson point processes on each street. Models in this Coxian framework can characterize streets of different lengths and orientations forming intersections or T-junctions. The lengths of the streets can be infinite or finite and mutually independent or dependent. We analyze the reliability of communication for different models, where reliability is the probability that a vehicle at an intersection, a T-junction, or a general location can receive a message successfully from a transmitter at a certain distance. Further, we introduce a notion of equivalence between vehicular models, which means that a representative model can be used as a proxy for other models in terms of reliability. Specifically, we prove that the Poisson stick process-based vehicular network is equivalent to the Poisson line process-based and Poisson lilypond model-based vehicular networks, and their rotational variants.

Endoscopic endoclip papilloplasty preserves sphincter of oddi function.

Endoscopic sphincterotomy (EST) can destroy sphincter of Oddi (SO) structure and function. The purpose of this study was to assess the feasibility of endoscopic endoclip papilloplasty (EEPP) in restoring SO function after EST. Seven 26-week-old domestic pigs were divided into control and EEPP groups. Necropsy and haematoxylin-eosin staining plus anti-α-smooth muscle actin (α-SMA) staining of papilla and sphincter of Oddi manometry (SOM) were conducted in animals at three independent time points. EST and EEPP were safely performed in all 7 pigs without serious adverse events. For primary outcome, compared to the controls, EEPP generated smaller dilation and less inflammation. Fibrous repair of the papilla was observed at 24weeks after EEPP. For secondary outcome, in the control group, SO basal pressure (17.25±18.14 to 5.50±0.71mmHg), SO contraction amplitude (46.00±19.20 to 34.50±48.79mmHg), peak (4.50±4.04 to 1.50±2.12) and frequency (3.05±3.29 to 1.41±2.19/min) were reduced after EST. Further reductions to almost 0 of these SOM parameters were observed 3weeks later, including common bile duct pressure and SO contraction period. In contrast, in the EEPP group, these manometric data were recovered to pre-EST levels, including CBD pressure (11.5±7.31 vs 11±2.16mmHg), SO pressure (17.50±17.75 vs 18.20±21.39mmHg) and SO contraction amplitude (53.67±21.54 vs 60.00±36.08mmHg). However, no significant differences were observed between control and EEPP groups by Student t test. In this porcine study, EEPP accelerated and improved papillary healing after EST, further preserved SO function.