This paper analyzes enterprise investment capability based on quantitative analysis under data mining technology and selects cash flow as the key indicator of enterprise investment to make a ...predictive analysis of enterprise cash flow. The system of enterprise investment capacity indicators is constructed, and the relationship between cash flow and each quantitative is analyzed by the regression model. The case analysis of the enterprise financing structure and the risk of bank financial indicators were conducted separately, and the results showed that the financing structure of enterprise A was dominated by long-term borrowing, which accounted for more than 60% every year, followed by bonds payable, which accounted for between 10% and 30% every year. The return on assets of Bank A is between 15% and 20%, much higher than the other two banks.
In many clinical studies, evaluating the association between longitudinal and survival outcomes is of primary concern. For analyzing data from such studies, joint modeling of longitudinal and ...survival data becomes an appealing approach. In some applications, there are multiple longitudinal outcomes whose longitudinal pattern is difficult to describe by a parametric form. For such applications, existing research on joint modeling is limited. In this article, we develop a novel joint modeling method to fill the gap. In the new method, a local polynomial mixed‐effects model is used for describing the nonparametric longitudinal pattern of the multiple longitudinal outcomes. Two model estimation procedures, that is, the local EM algorithm and the local penalized quasi‐likelihood estimation, are explored. Practical guidelines for choosing tuning parameters and for variable selection are provided. The new method is justified by some theoretical arguments and numerical studies.
The Boltzmann distribution of electrons sets a fundamental barrier to lowering energy consumption in metal-oxide-semiconductor field-effect transistors (MOSFETs). Negative capacitance FET (NC-FET), ...as an emerging FET architecture, is promising to overcome this thermionic limit and build ultra-low-power consuming electronics. Here, we demonstrate steep-slope NC-FETs based on two-dimensional molybdenum disulfide and CuInP
S
(CIPS) van der Waals (vdW) heterostructure. The vdW NC-FET provides an average subthreshold swing (SS) less than the Boltzmann's limit for over seven decades of drain current, with a minimum SS of 28 mV dec
. Negligible hysteresis is achieved in NC-FETs with the thickness of CIPS less than 20 nm. A voltage gain of 24 is measured for vdW NC-FET logic inverter. Flexible vdW NC-FET is further demonstrated with sub-60 mV dec
switching characteristics under the bending radius down to 3.8 mm. These results demonstrate the great potential of vdW NC-FET for ultra-low-power and flexible applications.
Materials that can produce large controllable strains are widely used in shape memory devices, actuators and sensors
, and great efforts have been made to improve the strain output
. Among them, ...ferroelastic transitions underpin giant reversible strains in electrically driven ferroelectrics or piezoelectrics and thermally or magnetically driven shape memory alloys
. However, large-strain ferroelastic switching in conventional ferroelectrics is very challenging, while magnetic and thermal controls are not desirable for practical applications. Here we demonstrate a large shear strain of up to 21.5% in a hybrid ferroelectric, C
H
N(CH
)
CdCl
, which is two orders of magnitude greater than that in conventional ferroelectric polymers and oxides. It is achieved by inorganic bond switching and facilitated by structural confinement of the large organic moieties, which prevents undesired 180° polarization switching. Furthermore, Br substitution can soften the bonds, allowing a sizable shear piezoelectric coefficient (d
≈ 4,830 pm V
) at the Br-rich end of the solid solution, C
H
N(CH
)
CdBr
Cl
. The electromechanical properties of these compounds suggest their potential in lightweight and high-energy-density devices, and the strategy described here could inspire the development of next-generation piezoelectrics and electroactive materials based on hybrid ferroelectrics.
Many longitudinal studies are designed to monitor participants for major events related to the progression of diseases. Data arising from such longitudinal studies are usually subject to interval ...censoring since the events are only known to occur between two monitoring visits. In this work, we propose a new method to handle interval‐censored multistate data within a proportional hazards model framework where the hazard rate of events is modeled by a nonparametric function of time and the covariates affect the hazard rate proportionally. The main idea of this method is to simplify the likelihood functions of a discrete‐time multistate model through an approximation and the application of data augmentation techniques, where the assumed presence of censored information facilitates a simpler parameterization. Then the expectation‐maximization algorithm is used to estimate the parameters in the model. The performance of the proposed method is evaluated by numerical studies. Finally, the method is employed to analyze a dataset on tracking the advancement of coronary allograft vasculopathy following heart transplantation.
Abstract
Flexoelectricity induced by the strain gradient is attracting much attention due to its potential applications in electronic devices. Here, by combining a tunable flexoelectric effect and ...the ferroelectric photovoltaic effect, we demonstrate the continuous tunability of photoconductance in BiFeO
3
films. The BiFeO
3
film epitaxially grown on SrTiO
3
is transferred to a flexible substrate by dissolving a sacrificing layer. The tunable flexoelectricity is achieved by bending the flexible substrate which induces a nonuniform lattice distortion in BiFeO
3
and thus influences the inversion asymmetry of the film. Multilevel conductance is thus realized through the coupling between flexoelectric and ferroelectric photovoltaic effect in freestanding BiFeO
3
. The strain gradient induced multilevel photoconductance shows very good reproducibility by bending the flexible BiFeO
3
device. This control strategy offers an alternative degree of freedom to tailor the physical properties of flexible devices and thus provides a compelling toolbox for flexible materials in a wide range of applications.
The limited memory retention for a ferroelectric field-effect transistor has prevented the commercialization of its nonvolatile memory potential using the commercially available ferroelectrics. Here, ...we show a long-retention ferroelectric transistor memory cell featuring a metal-ferroelectric-metal-insulator-semiconductor architecture built from all van der Waals single crystals. Our device exhibits 17 mV dec
operation, a memory window larger than 3.8 V, and program/erase ratio greater than 10
. Thanks to the trap-free interfaces and the minimized depolarization effects via van der Waals engineering, more than 10
cycles endurance, a 10-year memory retention and sub-5 μs program/erase speed are achieved. A single pulse as short as 100 ns is enough for polarization reversal, and a 4-bit/cell operation of a van der Waals ferroelectric transistor is demonstrated under a 100 ns pulse train. These device characteristics suggest that van der Waals engineering is a promising direction to improve ferroelectronic memory performance and reliability for future applications.
Ferroelastic switching in ferroelectric/multiferroic oxides plays a crucial role in determining their dielectric, piezoelectric, and magnetoelectric properties. In thin films of these materials, ...however, substrate clamping is generally thought to limit the electric-field- or mechanical-force-driven responses to the local scale. Here, we report mechanical-force-induced large-area, non-local, collective ferroelastic domain switching in PbTiO
epitaxial thin films by tuning the misfit-strain to be near a phase boundary wherein c/a and a
/a
nanodomains coexist. Phenomenological models suggest that the collective, c-a-c-a ferroelastic switching arises from the small potential barrier between the degenerate domain structures, and the large anisotropy of a and c domains, which collectively generates much larger response and large-area domain propagation. Large-area, non-local response under small stimuli, unlike traditional local response to external field, provides an opportunity of unique response to local stimuli, which has potential for use in high-sensitivity pressure sensors and switches.
The effect of long-term straw return on crop yield, soil potassium（K） content, soil organic matter, and crop response to K from both straw and chemical K fertilizer（K_2SO_4） were investigated in a ...fixed site field experiment for winter wheat-summer maize rotation in 6 years for 12 seasons. The field experiment was located in northern part of North China Plain with a sandy soil in relatively low yield potential. Two factors, straw return and chemical K fertilizer, were studied with two levels in each factor. Field split design was employed, with two straw treatments, full straw return of previous crop（St） and no straw return, in main plots, and two chemical K fertilizer treatments, 0 and 60 kg K2 O ha~（–1）, as sub-plots. The results showed that straw return significantly increased yields of winter wheat and summer maize by 16.5 and 13.2% in average, respectively, and the positive effect of straw return to crop yield showed more effective in lower yield season. Straw return significantly increased K absorption by the crops, with significant increase in straw part. In treatment with straw return, the K content in crop straw increased by 15.9 and 21.8% in wheat and maize, respectively, compared with no straw return treatment. But, straw return had little effect on K content in grain of the crops. Straw return had significant influences on total K uptake by wheat and maize plants, with an increase of 32.7 and 30.9%, respectively. There was a significant correlation between crop yield and K uptake by the plant. To produce 100 kg grain, the wheat and maize plants absorbed 3.26 and 2.24 kg K2 O, respectively. The contents of soil available K and soil organic matter were significantly affected by the straw return with an increase of 6.07 and 23.0%, respectively, compared to no straw return treatment. K_2SO_4 application in rate of 60 kg K2 O ha~（–1） showed no significant effect on wheat and maize yield, K content in crop straw, total K uptake by the crops, soil available K content, and soil organic matter. The apparent K utilization rate（percentage of applied K absorbed by the crop in the season） showed difference for wheat and maize with different K sources. In wheat season, the K utilization rate from K_2SO_4 was higher than that from straw, while in maize season, the K utilization rate from straw was higher than that from chemical fertilizer. In the whole wheat-maize rotation system, the K absorption efficiency by the two crops from straw was higher than that from K_2SO_4.
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