Miracle-dz/UniFAR-FTUs huggingface dataset:
The fundamental theorem of algebra before Carl Friedrich Gauss

This is a paper about the first attemps of demonstration of the fundamental theorem of algebra. Before, we analyze the tie between complex numbers and the number of roots of an equation of n-th degree. In the second paragraph, we see the relation between integration and the fundamental theorem. Finally, we observe the linear differential equation with constant coefficients and Euler's position about the fundamental theorem, and then we consider d'Alembert's, Euler's and Laplace's demonstrations. It is a synthesis paper dedicated to Pere Menal, a colleague and a friend.
Very viscous horizontal convection

‘Horizontal convection’ arises when a temperature variation is imposed along a horizontal boundary of a finite fluid volume. Here we study the infinite-Prandtl-number limit relevant to very viscous fluids, motivated by the study of convection in glass furnaces. We consider a rectangular domain with insulating conditions on the sides and bottom, and a linear temperature gradient on the top. We describe steady states for a large range of aspect ratio A and Rayleigh number Ra, and find universal scalings for the transition from small to large Rayleigh numbers. At large Rayleigh number, the top boundary-layer thickness scales as Ra−1/5, with the circulation and heat flux scaling as Ra1/5. These scalings hold for both rigid and shear-free boundary conditions on the top or on the other boundaries, which is initially surprising, but is because the return flow is dominated by a horizontal intrusion immediately beneath the top boundary layer. A downwelling plume also forms on one side, but because of strong stratification in the interior, the volume flux it carries is much smaller than that of the horizontal intrusion, decaying as the inverse of the depth below the top boundary. The fluid in the plume detrains into the interior and then returns to the top boundary, thus forming a ‘filling box’. We find analytic solutions for the interior temperature and streamfunction and match them to a similarity solution for the plume. At depths comparable to the length of the top boundary the streamfunction has O(1) values and the temperature variations scale as 1/Ra. Transient calculations with a large, but finite, Prandtl number, show how the steady state is reached from hot and cold initial conditions.
Tomography-Based Determination of the Effective Thermal Conductivity of Fluid-Saturated Reticulate Porous Ceramics

The effective thermal conductivity of reticulate porous ceramics (RPCs) is determined based on the 3D digital representation of their pore-level geometry obtained by high-resolution multiscale computer tomography. Separation of scales is identified by tomographic scans at 30 μm digital resolution for the macroscopic reticulate structure and at 1 μm digital resolution for the microscopic strut structure. Finite volume discretization and successive over-relaxation on increasingly refined grids are applied to solve numerically the pore-scale conduction heat transfer for several subsets of the tomographic data with a ratio of fluid-to-solid thermal conductivity ranging from 10 -4 to 1. The effective thermal conductivities of the macroscopic reticulate structure and of the microscopic strut structure are then numerically calculated and compared with effective conductivity model predictions with optimized parameters. For the macroscale reticulate structure, the models by Dul'nev, Miller, Bhattachary and Boomsma and Poulikakos, yield satisfactory agreement. For the microscale strut structure, the classical porosity-based correlations such as Maxwell's upper bound and Loeb's models are suitable. Macroscopic and microscopic effective thermal conductivities are superimposed to yield the overall effective thermal conductivity of the composite RPC material. Results are limited to pure conduction and stagnant fluids or to situations where the solid phase dominates conduction heat transfer.
Rotating stellar collapse model for supernova SN 1987A

Consequences of a stellar collapse with a moderately rotating core are studied. If one assumes a core rotation corresponding to q = Jc/GM-squared of about 3 with J the total angular momentum and M the gravitational mass of the core, the core collapse is likely to leave protoneutron stars a binary which coalesces in several seconds emitting the gravitational radiation. Characteristically this scenario yields two bursts of the neutrino emission a few seconds apart, one at the time of the collapse and the other at the coalescence, as indicated by the Kamiokande observation for SN 1987A. Some implications for future observations are also mentioned. 43 references.
Constitutive equations in suspension mechanics. Part 1. General formulation

Neither the phenomenological nor the structural approach to the determination of constitutive equations has yet shown itself to be capable of producing useful and predictive descriptions of the majority of technologically important complex fluids. In the present paper we explore the suggestion that significant progress can be made when these two complementary approaches to rheology are combined. For this initial study we restrict our attention to materials which can be modelled as a suspension of particles in a Newtonian fluid, thereby including most polymer solutions while excluding polymer melts. By applying phenomenological techniques to the basic formulation of suspension mechanics we are able to deduce a common simplified constitutive model for all suspension-like materials and to reveal its physical origin. The present analysis demonstrates that the constitutive model of Hand (1962), involving a single second-order tensor, is not sufficiently general for a rigorous description of the majority of suspension-like materials. Consideration of the constitutive forms for the limiting cases of near-equilibrium and strongly non-equilibrium microstructure suggests, however, that Hand's model may provide a reasonable approximation to the exact constitutive behaviour which is useful over the whole range of flow strengths.
Multiple Hydrogen Flashes on Accreting Low-Mass White Dwarfs: Novae and DAO Stars

We have computed 10 successive nova eruptions on two different mass white dwarfs as part of a study to determine the long-term evolution of cataclysmic binaries. The evolution of two low-mass white dwarfs, accreting hydrogen-rich matter at a rate of 10 −9 M ○. yr −1 -typical of close binary systems-was calculated by means of a hydrodynamic code. The code includes algorithms for diffusion and mass-loss, and is capable of computing continuously several cycles, by adjusting the time steps to the prevailing evolutionary time scale. A 0.6 M ○. white dwarf, composed of carbon and oxygen, and a 0.4 M ○. helium white dwarf are considered, both of low intrinsic luminosity
NEUTRON STARS IN INTERACTING BINARY SYSTEMS

The early history of the development of our understanding of neutron stars has been described by others, and we summarize it only briefly here. Following an early speculation by Baade & Zwicky ( 1934) soon after the discovery of the neutron in 1932, Oppenheimer & Volkoff(1939) presented a classic analysis of the theoretical viability of neutron stars, based on the general theory of relativity and the nuclear physics that was then known. A number of further theoretical studies were published during the next three decades, but it seemed that neutron stars might be virtually unobservable and thus remain little more than a theorist's curiosity piece. In a prophetic paper, Pacini (1967) noted that a rotating neutron star with a magnetic field whose axis was misaligned with the rotation axis should emit intense magnetic dipole radiation. Almost immediately thereafter (but quite independently), Hewish et al. (1968a,b) announced the discovery of radio pulsars. For a brief period, several theoretical models for the pulsar phenomenon were in contention. However, the discovery of the pulsar NP 0532 in the Crab Nebula (Staelin & Reifenstein i968, Comella et al. 1 969), followed by a notably straightforward set of observations and theoretical arguments, soon clinched the case for neutron stars (Gold 1969a). 1 (For a review of these remarkable developments, see Gold 1969b.)
Diagnosis of skin cancer using image processing

In this papera methodology for classifying skin cancerin images of dermatologie spots based on spectral analysis using the K-law Fourier non-lineartechnique is presented. The image is segmented and binarized to build the function that contains the interest area. The image is divided into their respective RGB channels to obtain the spectral properties of each channel. The green channel contains more information and therefore this channel is always chosen. This information is point to point multiplied by a binary mask and to this result a Fourier transform is applied written in nonlinear form. If the real part of this spectrum is positive, the spectral density takeunit values, otherwise are zero. Finally the ratio of the sum of the unit values of the spectral density with the sum of values of the binary mask are calculated. This ratio is called spectral index. When the value calculated is in the spectral index range three types of cancer can be detected. Values found out of this range are benign injure.
Test of the Fixed Anvil Temperature Hypothesis

AbstractThe fixed anvil temperature (FAT) hypothesis is examined based on the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS)-based cloud-top temperature (CTT) in conjunction with the tropical atmospheric profiles and sea surface temperature (SST) from the European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Reanalysis. Consistent with the physical governing mechanism of the FAT hypothesis, the peak clear-sky diabatic subsidence and convergence profiles are located at roughly the same level (200 hPa) as the peak in the cloud profile, which is fundamentally determined by the rapid decrease of water vapor concentration above this level. The geographical maxima of cloud fraction agree well with those of water vapor, clear-sky cooling rates, and diabatic convergence at 200 hPa. The use of direct CTT measurements suggests the CTT in specific Pacific basins exhibit different characteristics as the frequency distribution of the tropical SST varies from boreal winter to summer. When avera.
Tribology of PFPE overcoated self-assembled monolayers deposited on Si surface

Friction and wear characteristics of monomolecular layers of self-assembled monolayers (SAMs) with and without perfluoropolyether (PFPE) overcoat were studied using ball-on-disk experiments. Ultra-thin layer of PFPE was dip-coated onto two different SAMs, one with non-reactive terminal group (octadecyltrichlorosilane (OTS)) and the other with reactive terminal group (3-aminopropyltrimethoxysilane (APTMS)), which were formed on Si substrate by self-assembly. The effects of PFPE overcoating on physical and chemical properties were evaluated using contact angle measurement and x-ray photoelectron spectroscopy. For a comparison, PFPE was also coated onto the Si surface and their properties were evaluated. All PFPE modified surfaces were baked at 150°C for 2 h, to investigate the effect of thermal treatment on tribological properties. PFPE coating has shown higher water contact angles irrespective of the SAM surface. Coating of PFPE on both SAM surfaces has lowered their coefficients of friction. PFPE overcoating has shown remarkable increase in the wear resistance when it was coated on reactive APTMS SAM and little increase on OTS SAM. Thermal treatment after PFPE coating onto SAMs further reduced the coefficient of friction to a smaller extent. Moreover, thermal treatment has shown an additional increase in wear-life by approximately 30% in the case of PFPE coated APTMS SAM surface and a decrease in the wear-life in the case of PFPE coated OTS SAM. The reasons for these observed phenomena are explained in terms of the amounts of PFPE bonded or mobile, surface energies of SAMs, uniformity and molecular packing of SAM surfaces.
System reliability under cascading failure models with different load effect modes

Cascading failure is a phenomenon that minor disturbances trigger a chain reaction failure of the system, causing the disaster to quickly spread in the system and causing part or all of the system to collapse. Traditional cascading models that based on the assumption that the propagation time of cascading failures can be ignored are inadequate for modeling and analyzing all the practical cascading failure systems. It is necessary to develop a general methodology for the cascading failure systems with cascading failure propagation speed and different load effects. This paper derives new models which extend the load effect mode and consider the propagation speed of cascading failure. In the models, the time of the cascading failure propagation is considered. Three load effect modes are proposed that consider the number of remaining working components, the influence range of the failed parts, and the distance between the failed parts and the unfailed components. Additionally, the reliability of the systems with different types of cascading failures is analyzed, and formulas computing reliability indexes are derived. Numerical examples are provided to demonstrate the application of the proposed methodology.
Typical wire clamps segmentation of transmission lines based on infrared image

In view of the current image segmentation field, there are few studies on the segmentation of typical wire clamp components of transmission lines. Traditional image processing methods have low segmentation accuracy and require artificial design of feature extraction methods, which are usually only suitable for equipment of a certain structure with insufficient generalization. In this paper, an infrared image segmentation method based on Mask R-CNN (Mask region-based convolutional neural network) for typical guide-ground lines is proposed. Its structure takes Mask R-CNN model combined with FPN (Feature pyramid structure) as the basic framework, and uses RPN (Regional proposal network) to generate candidate regions. Features are extracted from each candidate region through RoI Align layer, and then connected to FC (Fully connected layer) to achieve target classification and bbox (bounding box) regression. A mask branch is also added to predict the segmentation mask. The design can integrate multi-scale and multi-level semantic information to improve the recognition rate when extracting image features. In addition, the network structure is optimized by single channel for infrared images to reduce the size of the model and make it more lightweight. Ablation experiments were performed on two GTX 2080Ti graphics cards to verify the effectiveness of the proposed structure, and the mAP (mean average accuracy) of 0.421 was achieved with an IoU (Intersection over Union) threshold of 0.5.
The Velocity Structure of Large Magellanic Cloud Carbon Stars: Young Disk, Old Disk, and Perhaps a Separate Population

We analyze the velocity residuals of 551 carbon stars relative to a rotating-disk model of the inner ~70 deg2 of the Large Magellanic Cloud (LMC). We find that the great majority of the stars in this sample are best fitted as being due to two different populations, a young disk population containing 20% of the stars with a velocity dispersion of 8 km s-1 and an old disk containing the remaining stars with a velocity dispersion of 22 km s-1. The young disk population has a metallicity ~0.25 dex higher than that of the old disk. With less certainty, the data also suggest at the 2 σ level that there may be a third kinematically distinct population that is moving toward us at 30 km s-1 relative to the LMC, consistent with measurements of 21 cm velocities. If real, this population contains about 7% of the carbon stars in the sample. It could be a feature in the disk of the LMC, or it could be tidal debris in the foreground or background. If it is tidal debris, this population could account for some or all of the microlensing events observed toward the LMC.
Predicting Age and Gender Using AlexNet

Due to the availability of technology stemming from in-depth research in this sector and the drawbacks of other identifying methods, biometrics has drawn maximum attention and established itself as the most reliable alternative for recognition in recent years. Efforts are still being made to develop a user-friendly system that is up to par with security-system requirements and yields more reliable outcomes while safeguarding assets and ensuring privacy. Human age estimation and Gender identification are both challenging endeavours. Biomarkers and methods for determining biological age and gender have been extensively researched, and each has advantages and disadvantages. Facial-image-based positioning is crucial for many applications, including safety and security systems, border control, human engagement in sophisticated ambient analytics, and biometric identification. Determining a person's age and gender is a complex study method. With the advent of deep learning, the study of face systems has been completely transformed, and estimation accuracy is a crucial parameter for evaluating algorithms and their efficacy in predicting absolute ages. The UTKFace dataset, which serves as the backbone of the face estimating system, was used to assess the method. The eyes, cheeks, nose, lips, and forehead provide the foundation of this function. AlexNet achieves a 98% accuracy rate across its lifespan of system results.
Accelerated methods for performing the LDLT decomposition

This paper describes the design, implementation and performance of parallel direct dense symmetric-indefinite matrix factorisation algorithms. These algorithms use the Bunch-Kaufman diagonal pivoting method. The starting point is numerically identical to LAPACK _sytrf() algorithm, but out-performs zsytrf() by approximately 15% for large matrices on the UltraSPARC family of processors. The first variant reduces symmetric interchanges, particularly important for parallel implementation, by taking into account the growth attained by any preceding columns that did not require any interchanges. However, it achieves the same growth bound. The second variant uses a lookahead technique with heuristic methods to predict whether interchanges are required over the next block column; if so, the block column can be eliminated using modified Cholesky methods, which can yield both computational and communication advantages. These algorithms yield best performance gains on `weakly indefinite' matrices (i.e. those which have generally large diagonal elements), which often arise from electro-magnetic field analysis applications. On UltraSPARC processors, the first variant generally achieves a 1--2% performance gain; the second is faster still for large matrices by 2% for complex double precision and 6% for double precision. However, larger performance gains are observed on distributed memory machines, where symmetric interchanges are relatively more expensive. On a 16 node 300MHz UltraSPARC-based Fujitsu AP3000, the first variant achieved a 10-15% improvement for small-moderate sized matrices, decreasing to 7% for large matrices. For N=10000 , it achieved a sustained speed of 5.6GFLOPs and a parallel speedup of 12.8.
Leu72Met Polymorphism in Ghrelin Gene: A Potential Risk Factor for Hypertension in Type 2 Diabetes Patients

Objective Ghrelin (GHRL) is known to be engaged in metabolic and cardiovascular processes. There is evidence suggesting its involvement in the regulation of blood pressure and hypertension. The purpose of this preliminary case–control study was to determine the involvement of the Leu72Met (rs696217) polymorphism in the GHRL gene in type 2 diabetes (T2DM). Methods The Leu72Met polymorphism was genotyped in 820 individuals with T2DM and 400 healthy subjects by the PCR-RFLP technique. The polymorphism distribution was first compared in those withT2DM and controls, then in subgroups of participants representing different clinical phenotypes. Results No significant association was identified between Leu72Met and T2DM. The distribution of polymorphism was analyzed in subgroups of individuals with different clinical phenotypes (hypertension, diabetic nephropathy, obesity). In this analysis, rs696217 was associated with hypertension. The presence of T allele was associated with higher risk of hypertension (OR = 2.50, 95% CI 1.68–3.73, p < 0.001). When adjusted for age, gender and BMI, the association was still significant (OR = 2.62, 95% CI 1.83–3.96, p < 0.001). A post hoc power calculations based on a minor allele frequency revealed the power of 97% for comparison between HY+ and HY- subgroups. Conclusion This is the first study demonstrating that the ghrelin Leu72Met SNP is associated with hypertension in Caucasians with T2DM. If confirmed in larger studies in different populations, it may be a novel potential risk factor for hypertension in individuals withT2DM.
Comb-Search and Hierarchical-Clustering Based Doppler-Shift Acquisition for Space Communications

In space communications, the signal quality generally suffers due to long-distance transmission and high dynamic movement. Long-distance transmission causes a very low signal-to-noise ratio (SNR) and high dynamic movement causes a dynamic Doppler-shift on carrier frequency. To boost the signal component in SNR, multiple symbols over a long duration of time are accumulated, which is termed as long-term accumulation. However, during the long-term accumulation, the large acceleration and jerk result in a time-varying Doppler shift, thus dispersing the energy over a wide frequency range. In this paper, we propose a comb-search and hierarchical-clustering (CSHC) based Doppler-shift acquisition scheme, including the Generic CSHC algorithm and Iterative CSHC algorithm, to address the energy dispersion problem for space communications. In the Generic CSHC algorithm, the comb-search (CS) decreases the noise energy by a narrower CS-range while the hierarchical-clustering (HC) increases the signal energy by clustering multiple signal elements into one signal cluster. Then, the Iterative CSHC algorithm, which builds on the iterations of CS and HC, further decreases the noise energy and increases the signal energy. Simulations results verify that our proposed CSHC scheme significantly improves the acquisition probability, as compared with the existing schemes.
Two-dimensional higher-order wavelet-like basis functions in the finite element method

Wavelets and wavelet analysis have recently become increasingly important in the computational sciences. Wavelets have many applications in areas such as signal analysis, image compression, and the numerical solution of partial differential equations and integral equations. For instance, two-dimensional wavelet-like basis functions are used in the numerical solution of elliptic partial differential equations. With diagonal preconditioning, the use of these wavelet-like basis functions yields a system matrix that has a condition number that is bounded by a constant as the number of basis functions is increased. These two-dimensional wavelet-like functions are derived directly from the traditional two-dimensional first order finite element basis functions. Typically, however, higher dimensional wavelets are formed from products of one-dimensional wavelets. Thus, in this paper we consider this alternative method for generating wavelet-like basis functions. Specifically, we investigate the generation of higher order two-dimensional wavelet-like basis functions from products of higher order one-dimensional wavelet-like basis functions. A discussion of the advantages and disadvantages of this new approach will be presented.