Miracle-dz/UniFAR-FTUs huggingface dataset:
Estimates on the non-compact expanding gradient Ricci solitons

Abstract In this paper, we deal with the complete non-compact expanding gradient Ricci soliton (Mn,g) with positive Ricci curvature. On the condition that the Ricci curvature is positive and the scalar curvature approaches 0 towards infinity, we derive a useful estimate on the growth of potential functions. Based on this and under the same assumptions, we prove that ∫t0 Rc (γ'(s) , γ' (s))ds and ∫t0 Rc (γ' (,s). v)ds at least have linear growth, where 7(5) is a minimal normal geodesic emanating from the point where R obtains its maximum. Furthermore, some other results on the Ricci curvature are also obtained.
Considerations on the use of spectroelectrochemistry in reflection mode for quantitative analysis: Study of the Fe(III)/Fe(II) – orthophenanthroline system

Theoretical and experimental considerations are made about possible analytical applications of spectroelec- trochemistry (SEC) in reflection mode using screen-printed electrodes. The system Fe(III)/Fe(II) – orthophenanthroline is taken as a model of electrochemical generation and consumption of a substance that is strongly absorbing: the Fe(II) – orthophenanthroline complex. Different possibilities of quantification are discussed, including cathodic and anodic peaks in cyclic voltammetry and both electrochemical and optical signals acquired in chronoamperometric experiments. Among these, the evolution of absorbance with the square root of time at a constant potential has shown interesting possibilities for the determination of Fe(III)-ion at micromolar level (LOD = 2 10 -6 mol L -1 ). Moreover, this method appears to be resistant to the presence of other electroactive species such as Cu(II)-ions.
Utilization of High-Power LEDs at Low-Cost Non-Invasive X-ray KV Meter Detectors Design

X-ray radiation is used to diagnose human body. In order to apply this method, two parameters are commonly used as the settings. The first is the KV value and the second is the mA value. In this case, when an error occurs in the kV setting, it will cause poor image quality, thus leads to inaccurate information in patient ’s examination. It is likewise the presence of excessive doses to the patient's body. To ensure that the KV value produced is under the settings on the machine consul, both invasive and non-invasive measurements were carried out. Non-invasive is becoming an easy standard to do. Several types of equipment on the market and research results have been widely used for this non-invasive activity. The problem emerges is that the existing tools still use expensive detectors. The purpose of this study was to design a low-cost non-invasive x-ray KV meter detector using an LED detector whose ability was tested at each point of collimation. Furthermore, the method used in this study was to stump the detectors at 4 ends of the collimation by 20 cm apart. The data were taken by doing x-ray exposure at a distance of 60 cm. The module measurements were carried out under 80 mA exposure conditions for 1 second and a collimation area of 20 x 20 cm. Meanwhile, the x-ray exposure settings were performed at 40kV, 50kV, 60kV, and 70kV settings. The module measurement results were further compared to the x-ray machine setting values. Based on the comparison results, the smallest error rate was obtained on Sensor 2 by 0.83%, while the highest error rate was obtained on S5 by 6.43%. The results can be concluded that the LED phosphor can capture x-rays, but the detector was weak due to the interference from ambient light. In addition, the results obtained from the detector itself were still less stable and linear. Furthermore, the implications of the results of this study are the initial basis for the use of high-power LEDs as sensors in non-invasive X-ray KV factor detection. In future research, stability and linearity should be built using a mechanical design that is able to reduce the ambient light interference.
Indicator and stratification methods for missing explanatory variables in multiple linear regression

Abstract The statistical literature and folklore contain many methods for handling missing explanatory variable data in multiple linear regression. One such approach is to incorporate into the regression model an indicator variable for whether an explanatory variable is observed. Another approach is to stratify the model based on the range of values for an explanatory variable, with a separate stratum for those individuals in which the explanatory variable is missing. For a least squares regression analysis using either of these two missing-data approaches, the exact biases of the estimators for the regression coefficients and the residual variance are derived and reported. The complete-case analysis, in which individuals with any missing data are omitted, is also investigated theoretically and is found to be free of bias in many situations, though often wasteful of information. A numerical evaluation of the bias of two missing-indicator methods and the complete-case analysis is reported. The missing-indi.
Bessel harmonic analysis and approximation of functions on the half-line

We study problems of approximation of functions on? in the metric of? with power weight using generalized Bessel shifts. We prove analogues of direct Jackson theorems for the modulus of smoothness of arbitrary order defined in terms of generalized Bessel shifts. We establish the equivalence of the modulus of smoothness and the -functional. We define function spaces of Nikol'skii-Besov type and describe them in terms? of best approximations. As a? tool for approximation, we use a? certain class of entire functions of exponential type. In this class, we prove analogues of Bernstein's inequality and others for the Bessel differential operator and its fractional powers. The main tool we use to solve these problems is Bessel harmonic analysis.
A Theory for the Forcing and Dissipation in Stochastic Turbulence Models

Abstract Recent studies reveal that randomly forced linear models can produce realistic statistics for inhomogeneous turbulence. The random forcing and linear dissipation in these models parameterize the effect of nonlinear interactions. Due to lack of a reasonable theory to do otherwise, many studies assume that the random forcing is homogeneous. In this paper, the homogeneous assumption is shown to fail in systems with sufficiently localized jets. An alternative theory is proposed whereby the rate of variance production by the random forcing and dissipation are assumed to be proportional to the variance of the response at every point in space. In this way, the stochastic forcing produces a response that drives itself. Different theories can be formulated according to different metrics for measuring “variance. ” This paper gives a methodology for obtaining the solution to such theories and the conditions that guarantee that the solution is unique. An explicit hypothesis for large-scale, rotating flows is .
Argo-Ybj Experiment Results and Prospects in Lhaaso Project

The ARGO-YBJ detector, a RPC carpet array at the high altitude of 4300 m has been stably operated since 2007. As a multi-purpose experiment the physics topics of ARGO-YBJ covers the VHE gamma-ray astronomy, cosmic ray physics and solar physics. Results of these experimental studies are reviewed. And as a future extension project, the Large High Altitude Air Shower Observatory (LHAASO) is introduced, some research and development of detectors are described.
Carbon nanotube composites with high dielectric constant at low percolation threshold

In this letter, the dielectric properties of the untreated multiwall carbon-nanotubes∕poly(vinylidene fluoride) (MWNT∕PVDF) composites are studied. Towards low frequencies, the dielectric constant of a composite with about 2.0vol% of MWNT increases rapidly and the value of the dielectric constant is as high as 300. However, by a calculation, the percolation threshold of the MWNT∕PVDF composites is only 1.61vol% (0.0161 volume fraction) of MWNT. Both the large aspect ratio and the high conductivity of the MWNT may lead to the low percolation threshold of the MWNT∕PVDF composites. For the percolation composite, the dielectric loss value is always less than 0.4, irrespective of the frequency. Therefore, the experimental results suggest that the dielectric properties of MWNT∕PVDF composites may be improved significantly without the chemical functionalization to carbon nanotubes.
Optimising fused filament fabrication surface roughness for a dental implant

ABSTRACT Medical applications of 3D Printing (3DP) have been investigated with dental implants and prosthetics since 2000. However, the use of 3DP in dental implants has been growing due to their ability to print scaffolds with functional characteristics. The present work optimizes a medical-dental implant 3D printed by the fused filament fabrication (FFF) technology in terms of three 3DPprocessing parameters, i.e. the infill rate (InfR), platform temperature (PlaT) and printing temperature (PriT). Furthermore, surface roughness is outlined in each case, and the parameter effects are explained while the printing time, shape quality and surface hardness are reported for the optimized implant. Additionally, a 3D printed dental implant with 0.16 mm Layer Thickness (LT) is utilized to show the pros and cons of the FFF technology versus the Poly Jet photopolymerization with 16 μm LT. Lastly, current challenges and future directions in FFF 3DP optimization issues of dental implants are also briefly outlined.
Research on autonomous dynamic real-time capture of robot based on hybrid prediction model

The trajectory of the dynamic target is an important basis for the robot to capture the action, and its advanced prediction precision plays a decisive role in achieving efficient capture. In this paper, a dynamic adaptive weighting method is proposed to establish a hybrid prediction model of GM (1,1) and SESM. The weights are allocated in real time, according to the prediction accuracy to improve the prediction accuracy of a single model and enhance the applicability of spatial trajectory prediction. Then, based on the rolling prediction principle, a high-precision advanced prediction method of the hybrid model is created. Compared with the advanced prediction of the model itself, the average prediction errors of the spatial arc and straight line verification trajectories are reduced by 40.26% and 49.77% respectively. The simulation model of robot dynamic target capture is built in Matlab, and the measured trajectory is used as the target trajectory. The robot capture experiment platform is built, and the target motion trajectory is collected by the camera in real time to capture the experiment, which verifies the effectiveness of the proposed method in actual capture.
Study on strengthening and toughening of sintered rare-earth permanent magnets

In recent years, we have a systematic investigation on the mechanical properties, fracture behavior and micromechanism, strengthening and toughening, and impact stability of sintered rare-earth permanent magnets (being abbreviated to “REPM”) at the aim of improving the workability and increasing the dynamic applications of REPM. A scanning electron microscope was used to study the fracture behavior and micromechanism of the experimental magnets. The impact stability of REPM was investigated using a falling-weight impact tester and an impact-acceleration standard device based on laser interference technique. The brittleness index of B=Hv∕KC was used to appraise the workability of REPM. It shows that the fracture mechanism of sintered NdFeB magnets mainly appears intergranular fracture. Sintered Sm-Co magnets tend to cleavage fracture. The fracture behavior REPM obviously exhibit anisotropy. The mechanical strength of the experimental magnets prepared by dual-alloy sintering method surpassed 390MPa without .
Large Panels with Common Factors and Spatial Correlations

This paper considers the statistical analysis of large panel data sets where even after conditioning on common observed effects the cross section units might remain dependently distributed. This could arise when the cross section units are subject to unobserved common effects and/or if there are spill over effects due to spatial or other forms of local dependencies. The paper provides an overview of the literature on cross section dependence, introduces the concepts of time-specific weak and strong cross section dependence and shows that the commonly used spatial models are examples of weak cross section dependence. It is then established that the Common Correlated Effects (CCE) estimator of panel data model with a multifactor error structure, recently advanced by Pesaran (2006), continues to provide consistent estimates of the slope coefficient, even in the presence of spatial error processes. Small sample properties of the CCE estimator under various patterns of cross section dependence, including spatial forms, are investigated by Monte Carlo experiments. Results show that the CCE approach works well in the presence of weak and/or strong cross sectionally correlated errors. We also explore the role of certain characteristics of spatial processes in determining the performance of CCE estimators, such as the form and intensity of spatial dependence, and the sparseness of the spatial weight matrix.
Dual-controller approach to three-dimensional autonomous formation control

The formation-keeping control problem is addressed for the three-dimensional autonomous formation flight of multiple aircraft. The full nonlinear kinematics model describing the relative position and orientation of the formation flight system is used to develop the nonlinear formation-keeping controllers. To deal with the input-output invertibility problem of the formation control system under consideration, a dual-controller approach is presented in this study. First, the original nonlinear formation system is decomposed into two subsystems. Next, the corresponding controller for each subsystem is developed. By invoking the nonlinear dynamic inversion-based control scheme and the well-known structure algorithm, an output-tracking controller with asymptotic stability is achieved for the first subsystem. The second subsystem is simple, and a relative roll angle-hold controller is designed to achieve an exponential convergence rate. Simulation results are provided to demonstrate the effectiveness of the proposed approach.
Two Notes on the Probabilistic Approach to Causality

1. According to the Humean theory of causality the individual event At (the event of kind A occurring at time t) caused Bt, (t' is assumed to be later than t) if and only if events of kind A are always followed by events of kind B. Many everyday examples of causal connections however refute this view, since it is seldom that the cause is always followed by the effect. Mumps, e.g., can cause sterility, but the probability of sterility given this illness is minimal. For those who wish to retain the basic idea of the Humean approach there seems to be two ways of solving the problem. The first, which I will call the deterministic approach, can be briefly described as follows. An event A can be construed as a set of more elementary events A , A2, . , An, and the statement that A occurs as a conjunction A occurs, A2 occurs, etc. We then introduce the following definitions:
Optimal output transitions for linear systems

Addresses the optimal output transition problem for linear systems. The goal is to transfer the system output from an initial value to a final output value with zero residual vibrations in the output. Such problems arise in the point-to-point positioning applications such as positioning of disk drive heads. Methods have been developed (previously) to achieve such output transition by constraining the internal states to be zero at the beginning and at the end of the output transition. The output transition problem is then solved as an optimal state transition problem. However, the output transition cost is not minimal. Output transition costs can be further reduced if the internal states are not constrained to be zero at the beginning and at the end of the output transition. The optimal output transition is posed and analytical solution is presented by (a) using the standard optimal state transition approach to obtain the control law during the output transition and then (b) integrating this with the inversion-based approach to find inputs that maintain perfect output tracking before the initiation and after the completion of the output transition by using pre- and post-actuation. An example system is studied and simulation results are presented to illustrate the performance improvement over approaches to point-to-point output transition, which do not use pre- and post-actuation.
Tutorial View of Electromagnetic Wave Diffraction Through Small Apertures Based on Energy Considerations

Abstract Electromagnetic wave diffraction through small apertures on perfectly electrically conducting surfaces is revisited in a tutorial spirit. Using solely energy arguments and the concept of radiation reaction fields, polarization formulas are obtained for aperture equivalent electric and magnetic dipoles in the presence of arbitrary sources or other apertures. Apertures on cavities are also treated with special attention to the role of cavity loss. The theory is applied to formulate the Foldy-Lax-type multiple scattering equations for aperture arrays on conducting planes.
Comment on “a PML‐FDTD formulation for the simulation of optical structures”

The focus of this comment is to discuss an important point regarding the derivation of the wave equation in the perfectly matched layer (PML). It is demonstrated that the distance dependency of the PML conductivity profile should be taken into consideration when deriving the wave equation in the PML region. Significant improvements in the absorbing performance are achieved with a small number of PML layers. A numerical test is carried out in one dimension to validate the proposed formulations. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 74–76, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10677
A structure adapted multipole method for electrostatic interactions in protein dynamics

We present an algorithm for rapid approximate evaluation of electrostatic interactions in molecular dynamics simulations of proteins. Traditional algorithms require computational work of the order O(N2) for a system of N particles. Truncation methods which try to avoid that effort entail untolerably large errors in forces, energies and other observables. Hierarchical multipole expansion algorithms, which can account for the electrostatics to numerical accuracy, scale with O(N log N) or even with O(N) if they become augmented by a sophisticated scheme for summing up forces. To further reduce the computational effort we propose an algorithm that also uses a hierarchical multipole scheme but considers only the first two multipole moments (i.e., charges and dipoles). Our strategy is based on the consideration that numerical accuracy may not be necessary to reproduce protein dynamics with sufficient correctness. As opposed to previous methods, our scheme for hierarchical decomposition is adjusted to structural.
The circular hydraulic jump

The circular hydraulic jump commonly forms on a horizontal plate struck by a vertical jet of liquid. New observations of this phenomenon are described. A previously unreported instability of the jump is examined. This is shown to arise when the local Reynolds number Rj just ahead of the jump exceeds a critical value of 147. Prior to this instability, the flow behind the jump contains a closed eddy, the length of which decreases to zero as Rj increases towards its critical value. Physical explanations for this flow structure and instability are proposed. Accurate measurements of liquid depths were made using a light-absorption technique, in which a laser was shone through water containing a strong dye. Liquid depths ahead of and behind the jump were so determined and depth profiles of the jump in the stable regime were obtained. As the outer depth was increased, the jump closed in on the jet and eventually disappeared: this extinction of the jump is also investigated.
Early Postoperative Cognitive Dysfunction in Women Undergoing Elective and Emergent Caesarian Section under General Anaesthesia: A Comparative Study

Background Postoperative cognitive dysfunction (POCD) following cesarean section (CS) is a growing and underestimated problem with unknown mechanisms. Studies suggest that general anesthesia (GA) plays a role in the development of early POCD. Objectives This study aimed to assess the incidence of early POCD after elective and emergent CS under GA. Methods We assessed the difference between the elective and emergent groups regarding the mini-mental state examination (MMSE), hemodynamic effects such as mean blood pressure (MBP), and heart rate (HR). Paired t-test was applied for intragroup comparison, and Student’s t-test (or Mann–Whitney U test, as appropriate) for intergroup comparison. Results MMSE one hour after the operation was significantly lower than preoperative MMSE in the emergent group, and the MMSE tended to return to normal values faster in the elective than in the emergent group. Moreover, we found a significantly lower MBP and higher HR (at 15, 30, and 45 minutes) in both groups compared to preoperative values. Regarding intergroup comparison, MBP (at 30 minutes) significantly decreased in the elective group compared to the emergent group. Conclusions There was a significantly lower POCD, especially at the first hour postoperatively, in the elective CS than in the emergent CS. Elective CS might have a positive effect on the women’s health as a mode of delivery.
Investigation of Thermal Analysis on the Process of Laser-Assisted Nanoimprinting Lithography

The technique of laser-assisted nanoimprinting lithography (LAN) has been proposed to utilize an excimer laser to irradiate through a quartz mold and melts a thin polymer film on the substrate for micro- to nano-scaled fabrications. This study introduces optical multiple reflection theory to demonstrate both analytical and numerical modeling during the LAN process and to predict the thermal response theoretically. Furthermore, the capability of energy absorption for polymer resist is examined herein. The temperature of polymer resist with the capability of energy absorption is much higher than that without energy absorption. This study demonstrates the characteristics of the energy absorption for polymer materials could improve the performance of the LAN process for the reason that the thermally affected region is extremely limited.