Characteristics Of Various Models Research Articles

Developing Mixed-Effects Models to Compare the Predictive Ability of Various Comorbidity Indices in a Contemporary Cohort of Patients Undergoing Lumbar Fusion.

As incidence of operative spinal pathology continues to grow, so do the rates of lumbar spinal fusion procedures. Comorbidity indices can be used preoperatively to predict potential complications. However, there is a paucity of research defining the optimal comorbidity indices in patients undergoing spinal fusion surgery. We aimed to use modeling strategies to evaluate the predictive validity of various comorbidity indices and combinations thereof. Patients who underwent spinal fusion were queried using data from the Nationwide Readmissions Database for the years 2016 through 2019. Using comorbidity indices as predictor variables, receiver operating characteristic curves were developed for pertinent complications such as mortality, nonroutine discharge, top-quartile cost, top-quartile length of stay, and 30-day readmission. A total of 750 183 patients were included. Nonroutine discharges occurred in 161 077 (21.5%) patients. The adjusted all-payer cost for the procedure was $37 616.97 ± $27 408.86 (top quartile: $45 409.20), and the length of stay was 4.1 ± 4.4 days (top quartile: 8.1 days). By comparing receiver operating characteristics of various models, it was found that models using Frailty + Elixhauser Comorbidity Index (ECI) as the primary predictor performed better than other models with statistically significant P -values on post hoc testing. However, for prediction of mortality, the model using Frailty + ECI was not better than the model using ECI alone ( P = .23), and for prediction of all-payer cost, the ECI model outperformed the models using frailty alone ( P < .0001) and the model using Frailty + ECI ( P < .0001). This investigation is the first to use big data and modeling strategies to delineate the relative predictive utility of the ECI and Johns Hopkins Adjusted Clinical Groups comorbidity indices for the prognostication of patients undergoing lumbar fusion surgery. With the knowledge gained from our models, spine surgeons, payers, and hospitals may be able to identify vulnerable patients more effectively within their practice who may require a higher degree of resource utilization.

Time-Dependent Rheological Properties of Cemented Aeolian Sand-Fly Ash Backfill Vary with Particles Size and Plasticizer.

The use of cemented Aeolian sand-fly ash backfill (CAFB) material to fill the mining area to improve the surface subsidence damage caused by underground coal mining is in the development stage. Their performance with large overflow water and strength loss is not well understood. Few research has been conducted to understand the effects of aeolian sand and coal gangue on the rheological properties of CAFB with plasticizers. Therefore, this study aims to investigate the effects of a plasticizer on the rheological properties, specifically yield stress and viscosity, of CAFB prepared with aeolian sand and coal gangue. CAFB mixes containing 0%, 0.05%, and 0.1% plasticizers were prepared, and yield stress and viscosity were determined at different intervals. Additional tests, such as thermal analysis and zeta potential analysis, were also conducted. It was found that the rheological properties of CAFB are the comprehensive manifestation of the composite characteristics of various models. Reasonable particle size distribution and less plasticizer can ensure the stability of the slurry structure and reduce the slurry settlement and the risk of pipe blocking. The findings of this study will be beneficial in the design and production of CAFB material.

An Effective Approach of Vehicle Detection Using Deep Learning.

With the rise of unmanned driving and intelligent transportation research, great progress has been made in vehicle detection technology. The purpose of this paper is employing the method of deep learning to study the vehicle detection algorithm, in which primary-stage target detection algorithms, namely, YOLOv3 algorithm and SSD algorithm, are adopted. Therefore, the method first processes the image data in the open-source road vehicle dataset for training. Then, the vehicle detection model is trained by using YOLOv3 and SSD algorithms to show the detection effect, respectively. The result is by comparing the detection effects of the two models on vehicles. The researchers accomplished the result analysis and summarized the characteristics of various models obtained by training, to apply to target tracking, semantic segmentation, and unmanned driving.

Complexity Analysis of E-Bayesian Estimation under Type-II Censoring with Application to Organ Transplant Blood Data

The E-Bayesian estimation approach has been presented for estimating the parameter and/or reliability characteristics of various models. Several investigations in the literature have considered this method under the assumption that just one parameter is unknown. So, based on Type-II censoring, this study proposes for the first time an effort to use the E-Bayesian estimation approach to estimate the full model parameters as well as certain related functions such as the reliability and hazard rate functions. To illustrate this purpose, we apply the proposed technique to the two-parameter generalized inverted exponential distribution which can be considered to be one of the most flexible asymmetrical probability distributions. Moreover, the E-Bayesian method, maximum likelihood, and Bayesian estimation approaches are also considered for comparison purposes. Under the assumption of independent gamma priors, the Bayes and E-Bayes estimators are developed using the symmetrical squared error loss function. Due to the complex form of the joint posterior density, two approximation techniques, namely the Lindley and Markov chain Monte Carlo methods, are considered to carry out the Bayes and E-Bayes estimates and also to construct the associate credible intervals. Monte Carlo simulations are performed to assess the performance of the proposed estimators. To demonstrate the applicability of the proposed methods in real phenomenon, one real data set is analyzed and it shows that the proposed method is effective and easy to operate in a real-life scenario.

Numerical study of the vibration suppression effect of a new vibration suppression method based on a shielding wall

A deep underground laboratory is an important research site for fields such as particle physics, astrophysics and cosmology, which require not only sophisticated technology and precision instruments but also stable and interference-free research environments. Ground motion can introduce interference with some precision instruments, causing the instruments to fail to work normally with the highest accuracy and even causing serious errors. Therefore, effective vibration suppression measures play a vital role in underground laboratory research. Based on the shielding effect underground structures have on ground motions, a shielding wall is proposed as a new vibration suppression method. By simulating the ground motion characteristics of various models (background models, excavation models, and backfill models) in the Jinping Underground Laboratory, the high-efficiency vibration suppression effect of a shielding wall was demonstrated. The influence of different backfill conditions on the vibration suppression effect of the shielding wall was systematically analysed, and a nonbackfilled shielding wall was determined to be the best vibration suppression option. Moreover, the influence of the length, position and angle of the shielding wall on its vibration suppression effect and the potential application prospects of the shielding wall were also discussed. Shielding walls enrich and develop vibration suppression measures, providing a new method for the prevention and control of seismic hazards in underground laboratories and surface buildings under dynamic load conditions.

NUMERICAL SIMULATION AND ANALYSIS OF THE EFFICIENCY OF NATURAL VENTILATION IN INDUSTRIAL BUILDINGS

The aerodynamic characteristics of various models of ridge natural ventilation systems are analyzed by numerical simulation. The most effective designs of ridge ventilation systems from the point of view of the lowest aerodynamic resistance are found.

Course of Artificial Intelligence + Composition for Young Backbone Teachers

Based on the analysis of the needs in the education field, the basic application framework scenarios of the current artificial intelligence technology in the field of music education are constructed. The characteristics of various models (typed music model, Markov chain model, genetic algorithm model, neural network model, etc.) are used to improve the rule knowledge to form a practical and effective hybrid model. The innovation lies in combining non-note units (reproducing structures) in music composition to intelligently compose tracks by combining formulas and matrix data combinations. The project conducts in-depth cooperation on the training of composition teachers and students from the fields of curriculum teaching, practical teaching, and innovation competition, and strives to combine theoretical teaching and engineering cases, practical teaching and industrial products, subject competition and intelligent technology. Combination to achieve collaborative education of industry-academia cooperation.

Mode analysis method for the computation of guided wave dispersion in metal sheet

Mode analysis method based on finite element theory is proposed to plot dispersion curves in metal sheet. This method is implemented by adopting COMSOL software to numerically solve and plot the dispersion curves. Compared with results obtained by semi-analytical finite element method, the calculating results are basically consistent and the modal caused by mode blending is obtained, which proves the mode analysis method is effective. Finally, the wave structure characteristics of various models are analysed, this provides a basis for the application of ultrasonic guided wave testing.

A Conceptual Framework for Modelling Spatial Relations

Various approaches lie behind the modelling of spatial relations, which is a heterogeneous and interdisciplinary field. In this paper, we introduce a conceptual framework to describe the characteristics of various models and how they relate each other. A first categorization is made among three representation levels: geometric, computational, and user. At the geometric level, spatial objects can be seen as point-sets and relations can be formally defined at the mathematical level. At the computational level, objects are represented as data types and relations are computed via spatial operators. At the user level, objects and relations belong to a context-dependent user ontology. Another way of providing a categorization is following the underlying geometric space that describes the relations: we distinguish among topologic, projective, and metric relations. Then, we consider the cardinality of spatial relations, which is defined as the number of objects that participate in the relation. Another issue is the granularity at which the relation is described, ranging from general descriptions to very detailed ones. We also consider the dimension of the various geometric objects and the embedding space as a fundamental way of categorizing relations.

Public-private collaboration: A panacea to road assets management in Nigeria

The globalisation of trade and rise in national income has resulted in increased demand for transport infrastructure and services. Given its high and diverse functionality and wide range of beneficiaries, road infrastructure and services have become essential components of national transport systems. However, lack of access to basic all-weather, reliable and safe road infrastructure is a major challenge in developing countries. Therefore, this study focused on public-private collaborative management of road infrastructure in Nigeria. The research methodological approach adopted an extensive review of relevant literature and questionnaire survey. A critical evaluation of secondary data helped to articulate the characteristics of various models of public-private collaboration. The study population comprised public, private sectors and end-user stakeholders purposively selected from the geo-political zones of Nigeria. Primary data were analysed through SPSS version 20 along with inferential (Kruskal-Wallis Test) and descriptive (Relative Importance Index) statistical tools. The study uncovered new meaning and understanding in ‘trust’, and strongly advocated for an effective stakeholders’ collaboration in financing, construction, operation, maintenance and management of viable road infrastructure and services.

How postural behaviour in undisturbed upright stance can be used to assess the physical characteristics of various models of ankle orthoses

Objectives. To assess various ankle orthoses presenting different physical characteristics. Design. The postural performance in bi-pedal stance of 14 healthy adults was assessed during four different ankle orthoses conditions. Background. Resultant ankle stiffness is an important component in undisturbed upright postural regulation. Methods. The centre of pressure displacements issued from the force platform were used to compute the horizontal motions of the centre of gravity, the controlled variable, and those of the difference between the centre of pressure and the vertical projection of the centre of gravity from which ankle stiffness can be estimated. Their respective contribution was assessed through a frequency analysis and a fractional Brownian motion modelling to determine their spatio-temporal linkage and their degree of control. Results. Ligacast, the more rigid model, induces the larger decrease, principally in the medio-lateral direction, in both centre of pressure minus centre of gravity and centre of gravity amplitudes. Dynastab reduces only the centre of pressure minus centre of gravity motions in both medio-lateral and antero-posterior directions. Lastly, no specific effect was observed for the less rigid Ligaflex for each motion and each direction. These effects are mainly explained by a reduction in the distance covered until the corrective process is initiated, the corresponding time interval being unchanged. In addition, depending on the model, the corrective processes appear more or less controlled. Conclusions. Modulating the ankle joint stiffness by using various models of orthoses induces some contrasted behaviours, hence suggesting that postural control does not result solely from resultant ankle stiffness. Relevance This data, contributing to the understanding of orthotic devices by emphasising their benefits, allows the practitioners and physical therapists to take into account the specific effects generated by each model.

The object-oriented COBOL model

‘The object-oriented COBOL model’ will reassure the reader that COBOL is not dead nor is it dying. This paper explores characteristics of various models being considered for the new and extended object oriented version of the COBOL programming language. It contrasts the models behind the traditional COBOL language (relevant to 1959) and the new COBOL language (relevant to the 1990s). It includes a discussion of some criteria the Object Oriented COBOL Task Group (X3J4.1) is considering while defining the new object-oriented COBOL. Lastly, this paper presents a proposed time schedule for the revision of the 34 year old COBOL language.

Modelling optical fibres with arbitrary refractive-index profiles

The characteristics of various models of refractive-index profile are examined. Four models are considered: (1) power-law profile, (2) truncated even polynomial profile, (3) truncated all-term polynomial profile, (4) Gauss-Chebychev approximation. The characteristics of the various models are examined with particular reference to the ray-delay times and the shape of the impulse response. The results show that models (1) and (2) are limited in their usefulness in representing practical profiles, while the approximation (4) is easily applied to a variety of practical profiles.

The Development of High-Output Free-Piston Gas Generators

Abstract The development of free-piston gas generators suitable for naval-propulsion purposes was started in 1943 at the Baldwin-Lima-Hamilton Corporation, then the General Machinery Corporation, under a contract with the U. S. Navy Department. At that time little was known in this country regarding the free-piston developments of Pescara in France or Sulzer in Switzerland, which had already been under way for some years. This paper traces the progress made in this project and describes the construction and operating characteristics of various models which have been made during the course of the program.