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Clustering has been one of the most basic and essential problems in unsupervised learning due to various applications in many critical fields. The recently proposed sum-of-norms (SON) model by Pelckmans et al. (in: PASCAL workshop on statistics and optimization of clustering, 2005), Lindsten et al. (in: IEEE statistical signal processing workshop, 2011) and Hocking et al. (in: Proceedings of the 28th international conference on international conference on machine learning, 2011) has received a lot of attention. The advantage of the SON model is the theoretical guarantee in terms of perfect recovery, established by Sun et al. (J Mach Learn Res 22(9):1–32, 2018). It also provides great opportunities for designing efficient algorithms for solving the SON model. The semismooth Newton based augmented Lagrangian method by Sun et al. (2018) has demonstrated its superior performance over the alternating direction method of multipliers and the alternating minimization algorithm. In this paper, we propose a Euclidean distance matrix model based on the SON model. Exact recovery property is achieved under proper assumptions. An efficient majorization penalty algorithm is proposed to solve the resulting model. Extensive numerical experiments are conducted to demonstrate the efficiency of the proposed model and the majorization penalty algorithm. [ABSTRACT FROM AUTHOR]

The multi-principal-element alloys (MPEAs), also referred to as high-entropy alloys (HEAs), have attracted extensive attention during the last decade and a half due to their unique and excellent properties. However, many MPEAs show coarse and anisotropic columnar grains in the as-cast state. While constitutional supercooling (CS)-driven parameters have been widely used to evaluate and predict the effect of solutes on columnar-to-equiaxed transition (CET) and grain refinement of diluted binary alloys, similar studies are lacking on MPEAs. Due to the multiple solute elements (solutes) and their high concentrations, the CS-driven parameters for MPEAs are different from those proposed for diluted binary alloys. Here, we derived the CS-driven parameters, including undercooling parameter and growth restriction factor, for MPEAs based on their physical significances, with the help of calculated phase diagrams. The calculated CS-driven parameters were then used to predict the effect of a solute on CET and grain refinement in NiCoFeCr MPEAs. Additional alloying solutes Nb, Ti, and V in the NiCoFeCr MPEA were also evaluated for their different CS-driven characteristics. The grain size of the as-solidified microstructures of NiCoFeCr with and without Nb, Ti, and V were compared and interpreted with the predicted tendency of the CS-driven parameters. [ABSTRACT FROM AUTHOR]

Multi-principal element alloys (MPEAs) have been extensively studied in recent years. However, the as-cast MPEAs usually possess coarse columnar grains with undesirable properties, thus columnar-to-equiaxed transition (CET) and grain refinement are of great significance. According to the interdependence theory, increasing the constitutional supercooling (CS) and limiting the diffusion of solutes will result in a refined structure. Therefore, the effect of boron (B) element on grain refinement of the as-cast CoCrNi MPEAs was evaluated: B element accumulates in the region ahead of the solid–liquid (S–L) interface during solidification and has such a strong affinity with the Cr element that it can induce the segregation of Cr element and restrict the diffusion of Cr element. The results indicate that B element induces CET and grain refinement significantly. The grain refinement is attributed to CS ahead of the S–L interface caused by the interaction of solutes and the slower diffusion rate induced by the concentration of B element. This work proposed a new method to refine the microstructure of the MPEAs. [ABSTRACT FROM AUTHOR]

The CrMnFeCoNi high-entropy alloy (HEA) has attracted extensive attention due to its excellent ductility and fracture toughness. However, this kind of Cr-containing systems show a strong tendency to precipitate brittle sigma phases. Then, Cr was replaced by Cu to form an equatomic CuMnFeCoNi HEA to eliminate the sigma formation concern. To obtain uniform microstructure and superior mechanical properties, here we conducted thermomechanical processing (drop cast, homogenization, cold rolling and annealing) on this alloy and revealed the microstructure evolution and tensile properties after annealing for 1 hour at 850 °C, 900 °C, 1000 °C and 1100 °C, respectively. All HEAs show dual-phase face-centered-cubic (FCC) structures with slightly different lattice constants. Their microstructures are composed of equiaxed grains and Cu-rich precipitates. Increasing temperature leads to coarser grains and Cu-rich precipitates. As expected, the alloy after annealing at 900 °C/1 hour shows best tensile property with the yield strength of 419 MPa and elongation to fracture of 28 pct. Its superior tensile property can be ascribed to the abundant fine Cu-rich particles along grain boundaries and in intragranular regions. [ABSTRACT FROM AUTHOR]

In order to solve the problem of the separation of zeolites powder from disposal solution, the magnetic zeolites are synthesized by hydrothermal method. A series of zeolite samples with different iron content are reduced and characterized by X-ray diffraction, scanning electron microscopy, infrared spectroscopy, thermogravimetric and differential thermal analysis and magnetism testing. The results show that the crystalline structures of iron-incorporated zeolites are well integrated. When iron content in zeolites is low, the structure of iron-incorporated X zeolites is not changed, but it transforms to the same structure as 4A zeolites when the iron content is high. The iron-incorporated zeolites still maintain crystalline structure on hydrogen reduction below 700 °C, and their structures are destroyed completely when the reduction temperature rises up to 800 °C. The adsorptive experiments of fluoride ion and lead ion are carried out. The results show that the adsorption capacity of fluoride ions decreases slightly, but that of Pb2+ reaches the maximum when iron content is 2.98%. The magnetization process has little effect on the adsorption of F− and Pb2+. [ABSTRACT FROM AUTHOR]

As a promising engineering material, high-entropy alloys (HEAs) CrFeCoNi system has attracted extensive attention worldwide. Their cast alloys are of great importance because of their great formability of complex components, which can be further improved through the transition of the columnar to equiaxed grains and grain refinement. In the current work, the influence of C contents on the grain structures and mechanical properties of the as-cast high-entropy alloy CrFeCoNi was chosen as the target and systematically studied via a hybrid approach of the experiments and thermodynamic calculations. The alloys with various C additions were prepared by arc melting and drop cast. The as-cast macrostructure and microstructure were characterized using optical microscopy, scanning electron microscopy, and transmission electron microscopy. The cast HEAs transform from coarse columnar grains into equiaxed grains with the C level increased to ≥ 2 at. pct and the size of equiaxed grains is further decreased with the increasing C addition. It is revealed that the interdendritic segregation of Cr and C results in grain boundary precipitation of M23C6 carbides. The grain refinement is attributed to the additional constitutional supercoiling from the C addition. The yield stress and tensile strength at room temperature are improved due to the transition of columnar to equiaxed grains and grain refinement. [ABSTRACT FROM AUTHOR]

In this article, the stress-shielding effect of a Nitinol swan-like memory compressive connector (SMC) is evaluated. Patients with fracture healing of an upper limb after SMC internal fixation or stainless steel plate fixation were randomly selected and observed comparatively. With the informed consent of the SMC group, minimal cortical bone under the swan-body and swan-neck was harvested; and in the steel plate fixation group, minimal cortical bone under the steel plate and opposite side to the steel plate was also harvested for observation. Main outcome measurements were taken such as osteocyte morphology, Harversian canal histological observation under light microscope; radiographic observation of fracture healing, and computed tomography quantitative scanning of cortical bone. As a conclusion, SMC has a lesser stress-shielding effect to fixed bone than steel plate. Finally, the mechanism of the lesser stress-shielding effect of SMC is discussed. [ABSTRACT FROM AUTHOR]

The anisotropy of tin is associated with significant variations in its coefficient of thermal expansion and elastic modulus, with crystallographic direction. Under pure thermal cycling (with no externally applied stress or strain), substantial strains, in excess of 100%, may develop locally, and for very small structures, such as soldered interconnections comprising a few grains, structural integrity may be adversely affected. To examine this possibility, freestanding samples of tin, Sn-3.5wt.%Ag, Sn-0.5wt.%Cu, and Sn-3.8wt.%Ag-0.7wt.%Cu, have been subjected to thermal cycling. Temperature cycles from 30°C to 125°C or from -40°C to 55°C initially caused surface cracking, with openings up to several tens of microns after 3,000 cycles. Subsequently, the surface cracks grew into the interior of the specimens, with the maximum penetration ranging from a few microns after 100 cycles to more than 200 µm after 3,000 cycles. The cracks initiated from damage accumulated along grain boundaries. For the same temperature range, less damage resulted after the lower maximum (or mean) temperature cycle, and there appears to be a thermally activated component of cracking. The microstructure produced by rapid cooling (water quenching) was slightly more resistant than that formed by air, or furnace, cooling. Apart from microstructural coarsening, no damage accrues from isothermal exposure alone. [ABSTRACT FROM AUTHOR]

Stochastic programming has extensive applications in practical problems such as production planning and portfolio selection. Typically, the model has very large size and some techniques are often used to exploit the special structure of the programs. It has been noticed that the coefficient matrix may not be of full rank in the well-known scenario formulation of stochastic programming; thus, the preprocessing is often necessary in developing rapid decomposition methods. In this paper, we propose a parallelizable preprocessing method, which exploits effectively the structure of the formulation. Although the underlying idea is simple, the method turns out to be very useful in practice, since it may help us to select the nonanticipativity constraints efficiently. Some numerical results are reported confirming the usefulness of the method. [ABSTRACT FROM AUTHOR]

Increasing evidence suggests that tissue inhibitor of metalloproteinases-1 (TIMP-1) can directly regulate cell growth and apoptosis independent of its matrix metalloproteinases (MMPs)-inhibitory activity. While TIMP-1's antiapoptotic activity has been well demonstrated, conflicting data has been reported regarding TIMP-1's role in growth regulation. Here we show that TIMP-1 reduces the growth rate of human breast epithelial (MCF10A) cells by inducing cell cycle arrest at G1. TIMP-1-mediated cell cycle arrest is associated with its downregulation of cyclin D1 and upregulation of p27KIP1, resulting in inhibition of cyclin-dependent kinase activity necessary for phosphorylation of the tumor suppressor retinoblastoma protein. We further show that TIMP-1 modulation of cyclin D1 and p27KIP1 is achieved through TIMP-1-mediated differential regulation of protein stability independent of growth factor signaling. We also show that TIMP-1-mediated differential regulation of cyclin D1 and p27KIP1 is independent of cell adhesion signaling. Whereas approximately 50% of MCF10A cells with reduced TIMP-1 expression underwent cell death following loss of cell adhesion (anoikis), TIMP-1 overexpressing cells remained viable with prominent cell cycle arrest without detectable cell death. Taken together, we propose that TIMP-1-mediated cell survival independent of cell adhesion is accompanied with cell cycle arrest in human breast epithelial cells, although cell cycle regulation may not be a prerequisite for TIMP-1 regulation of apoptosis in general.Oncogene (2006) 25, 3041–3048. doi:10.1038/sj.onc.1209336; published online 9 January 2006 [ABSTRACT FROM AUTHOR]

In this paper, the authors propose the generic concept of machining instability based on the analysis of all kinds of machining instable behaviours and their features. The investigation covers all aspects of the machining process, including the machine tool structural response, cutting process variables, tooling geometry and workpiece material property in a full dynamic scenario. The paper presents a novel approach for coping with the sophisticated machining instability and enabling better understanding of its affect on the surface generation through a combination of the numerical method with the characteristic equations and using block diagrams/functions to represent implicit equations and non-linear factors. It therefore avoids the lengthy algebraic manipulations in deriving the outcome and the solution scheme is thus simple, robust and intuitive. Several machining case studies and their simulation results demonstrate the proposed approach is feasible for shop floor CNC machining optimisation in particular. The results also indicate the proposed approach is useful to monitor the machining instability and surface topography and to be potentially applied in adaptive control of the instability in real time. [ABSTRACT FROM AUTHOR]

An accurate cutting force model of ball-end milling is essential for precision prediction and compensation of tool deflection that dominantly determines the dimensional accuracy of the machined surface. This paper presents an improved theoretical dynamic cutting force model for ball-end milling. The three-dimensional instantaneous cutting forces acting on a single flute of a helical ball-end mill are integrated from the differential cutting force components on sliced elements of the flute along the cutter-axis direction. The size effect of undeformed chip thickness and the influence of the effective rake angle are considered in the formulation of the differential cutting forces based on the theory of oblique cutting. A set of half immersion slot milling tests is performed with a one-tooth solid carbide helical ball-end mill for the calibration of the cutting force coefficients. The recorded dynamic cutting forces are averaged to fit the theoretical model and yield the cutting force coefficients. The measured and simulated dynamic cutting forces are compared using the experimental calibrated cutting force coefficients, and there is a reasonable agreement. A further experimental verification of the dynamic cutting force model will be presented in a follow-up paper. [ABSTRACT FROM AUTHOR]

As noted by Wächter and Biegler (Ref. 1), a number of interior-point methods for nonlinear programming based on line-search strategy may generate a sequence converging to an infeasible point. We show that, by adopting a suitable merit function, a modified primal-dual equation, and proper line-search procedure, a class of interior-point methods of line-search type will generate a sequence such that either all the limit points of the sequence are KKT points, or one of the limit points is a Fritz John point, or one of the limit points is an infeasible point that is a stationary point minimizing a function measuring the extent of violation to the constraint system. The analysis does not depend on the regularity assumptions on the problem. Instead, it uses a set of satisfiable conditions on the algorithm implementation to drive the desired convergence property. [ABSTRACT FROM AUTHOR]

Cutting trials reveal that a measure of cutter run-out is always unavoidable in peripheral milling. This paper improves and extends the dynamic cutting force model of peripheral milling based on the theoretical analytical model presented in Part I [1], by taking into account the influence of the cutter run-out on the undeformed chip thickness. A set of slot milling tests with a single-fluted helical end-mill was carried out at different feed rates, while the 3D cutting force coefficients were calibrated using the averaged cutting forces. The measured and predicted cutting forces were compared using the experimentally identified force coefficients. The results indicate that the model provides a good prediction when the feed rate is limited to a specified interval, and the recorded cutting force curves give a different trend compared to other published results [8]. Subsequently, a series of peripheral milling tests with different helical end-mill were performed at different cutting parameters to validate the proposed dynamic cutting force model, and the cutting conditions were simulated and compared with the experimental results. The result demonstrates that only when the vibration between the cutter and workpiece is faint, the predicted and measured cutting forces are in good agreement. [ABSTRACT FROM AUTHOR]

We carry out Density Matrix Renormalization Group (DMRG) calculations on the interchain coupling model for the quasi-one-dimensional organic ferromagnets under open boundary condition. Considering the topology of the system, the two-step DMRG technique is adopted. It is found that in the high spin ground state of the system the interchain coupling is in favor of the stability of ferromagnetic state, and the on-site electron-electron repulsive interaction has the same effect. However the inter-site electron-electron interaction causes a charge density distribution along the main chain and weakens the stability of the ferromagnetic ground state. The lattice distortion along the main chain is also discussed. [ABSTRACT FROM AUTHOR]

Timing analysis of PSR J1705-1906 using data from Nanshan 25-m and Parkes 64-m radio telescopes, which span over fourteen years, shows that the pulsar exhibits significant proper motion, and rotation instability. We updated the astrometry parameters and the spin parameters of the pulsar. In order to minimize the effect of timing irregularities on measuring its position, we employ the Cholesky method to analyse the timing noise. We obtain the proper motion of −77(3) mas yr−1 in right ascension and −38(29) mas yr−1 in declination. The power spectrum of timing noise is analyzed for the first time, which gives the spectral exponent α=−5.2 for the power-law model indicating that the fluctuations in spin frequency and spin-down rate dominate the red noise. We detect two small glitches from this pulsar with fractional jump in spin frequency of Δν/ν∼2.9×10−10 around MJD 55199 and Δν/ν∼2.7×10−10 around MJD 55953. Investigations of pulse profile at different time segments suggest no significant changes in the pulse profiles around the two glitches. [ABSTRACT FROM AUTHOR]