Concise Analytical Model Research Articles

A concise analytical model for the ideal reverse osmosis desalination processes.

Permeate recovery is a key parameter that plays a central role in the performance assessment and optimization of reverse osmosis processes. It remains a great challenge for engineers in the field to determine the recovery conveniently and accurately from the basic parameters of a membrane system. A concise analytical model is presented here that, without the need for the empirical or fitting coefficients and tedious numerical calculation, links the recovery of a reverse osmosis process rigorously to three basic parameters: the feed water salt concentration, the characteristic of membrane process, and the driving pressure. A graphical solution method to the model is also introduced to find out the recovery effortlessly. The concise model and graphical method are demonstrated under various conditions as a powerful tool for the performance simulations and improvement of reverse osmosis processes. PRACTITIONER POINTS: A concise model is presented for permeate recovery in an ideal RO desalination system. The recovery of an RO system is analytically related to a few system parameters. A graphical solution method is introduced to find out the explicit recovery. The ideal RO model can be a powerful tool for simulation of RO processes.

A simple semiempirical model for the static polarizability of ions

Abstract A concise analytical model for the static dipole polarizability of ionized atoms and molecules is created for the first time. As input, it requires, alongside the polarizability of neutral counterpart of a given ion, only the charge and elemental composition. This physically motivated semiempirical model is based on a number of established regularities in polarizability of charged monatomic and polyatomic compounds. In order to adjust it, the results of quantum chemistry calculations and gas-phase measurements available for a broad range of ionized multielectron species are employed. To counteract the appreciable bias in the literature data toward polarizability of monoatomic ions, for some molecular ions of general concern the results of the authors’ own density functional theory calculations are additionally invoked. A total of 541 data points are used to optimize the model. It is demonstrated that the model we suggested has reasonable (given the substantial uncertainties of the reference data) accuracy in predicting the static isotropic polarizability of arbitrarily charged ions of any size and atomic composition. The resulting polarizability estimates are found to achieve a coefficient of determination of 0.93 for the assembled data set. The created analytic tool is universally applicable and might be advantageous for some applications, where there is an urgent need for rapid low-cost evaluation of the static gas-phase polarizability of ionized atoms and molecules. This is especially relevant to constructing the complex models of nonequilibrium chemical kinetics aimed at precise describing the observable refractive index (dielectric permittivity) of plasma flows. The data sets that support the findings of this study are openly available in Science Data Bank at https://...

Delamination initiation in fully clamped rectangular CFRP laminates subjected to out-of-plane quasi-static indentation loading

To further investigate the effects of in-plane and out-of-plane stresses on the delamination initiation for composite laminates under out-of-plane loading, this paper reports a joint experimental and numerical study, in which the fully clamped rectangular CFRP composite laminates were subjected to out-of-plane quasi-static indentations. The results show that the combination of the out-of-plane shear and in-plane tensile stresses together determined the initiation of delamination, whereas the influences of the out-of-plane compressive stress on the delamination initiation can be neglected. For the purpose of understanding the effects of deformations on the out-of-plane shear and compressive stress distributions, a concise analytical model was developed, which was validated against the numerical and experimental results. As a key take-away, this study reveals that the common impact tests at the geometric centre of the panel may not resemble sufficient similitude with stiffened panels where panel flexure is suppressed by various geometrical stiffening concepts.

Trauma-Informed Organizational Dynamics and Client Outcomes in Concurrent Disorder Treatment

Purpose: To test an empirical model of the effects of a trauma-informed organizational environment on service user outcomes in the context of concurrent disorder treatment. Methods: Service users ( n = 172) were surveyed while in treatment to determine the effects of trauma-informed organizational dynamics (i.e., safety, trust, choice, collaboration, and empowerment) on service user intrapersonal development outcomes (i.e., self-awareness, outlook, coping ability, self-worth, and self-determination) and improvements with concurrent disorder behaviors. After testing for validity and reliability of latent factors, data were analyzed using multivariate analysis. Results: As a concise analytical model, the trauma-informed organizational environment was found to significantly positively predict all service user intrapersonal outcomes as well as a reduction in concurrent disorder behaviors. Conclusions: This study informs developments in the design and implementation of trauma-informed practice frameworks for concurrent disorder treatment and emphasizes the importance of adapting organizational environments to support improved client outcomes.

Effect of Liposomal Encapsulation on the Chemical Exchange Properties of Diamagnetic CEST Agents.

Exogenous chemical exchange saturation transfer (CEST) contrast agents such as glucose or 2-deoxy-d-glucose (2-DG) have shown high sensitivities and significant potential for monitoring glucose uptake in tumors with MRI. Here, we show that liposome encapsulation of such agents can be exploited to enhance the CEST signal by reducing the overall apparent exchange rate. We have developed a concise analytical model to describe the liposomal contrast dependence on several parameters such as pH, temperature, irradiation amplitude, and intraliposomal water content. This is the first study in which a model has been constructed to measure the exchange properties of diamagnetic CEST agents encapsulated inside liposomes. Experimentally measured exchange rates of glucose and 2-DG in the liposomal system were found to be reduced due to the intermembrane exchange between the intra- and extraliposomal compartments because of restrictions in water transfer imposed by the lipid membrane. These new theoretical and experimental findings will benefit applications of diamagnetic liposomes to image biological processes. In addition, combining this analytical model with measurements of the CEST signal enhancement using liposomes as a model membrane system is an important new general technique for studying membrane permeability.

A Quantitative Survey of the Power Saving Potential in IP-Over-WDM Backbone Networks

The power consumption in Information and Communication Technologies networks is growing year by year; this growth presents challenges from technical, economic, and environmental points of view. This has lead to a great number of research publications on “green” telecommunication networks. In response, a number of survey works have appeared as well. However, with respect to backbone networks, most survey works: 1) do not allow for an easy cross validation of the savings reported in the various works and 2) nor do they provide a clear overview of the individual and combined power saving potentials. Therefore, in this paper, we survey the reported saving potential in IP-over-WDM backbone telecommunication networks across the existing body of research in that area. We do this by mapping more than ten different approaches to a concise analytical model, which allows us to estimate the combined power reduction potential. Our estimates indicate that the power reduction potential of the once-only approaches is 2.3 $\times$ in a Moderate Effort scenario and 31 $\times$ in a Best Effort scenario. Factoring in the historic and projected yearly efficiency improvements (“Moore's law”) roughly doubles both values on a ten-year horizon. The large difference between the outcome of Moderate Effort and Best Effort scenarios is explained by the disparity and lack of clarity of the reported saving results and by our (partly) subjective assessment of the feasibility of the proposed approaches. The Moderate Effort scenario will not be sufficient to counter the projected traffic growth, although the Best Effort scenario indicates that sufficient potential is likely available. The largest isolated power reduction potential is available in improving the power associated with cooling and power provisioning and applying sleep modes to overdimensioned equipment.

Theoretical model for manipulating light distribution in the time domain by using a spatially homogenous dynamic medium

A concise analytical model has been reported for investigating the modulation of light using a dynamic medium, under two rather general assumptions. Based on this model, a phenomenon called time-domain imaging has been predicted which is that, after the modulation by the dynamic medium linearly changing with time, an arbitrary input light can be converted into an output light with temporal distribution having the geometric similarity to that of the input light, much like the spatial imaging of an optical lens, except for time retardation. This prediction agrees with the finite-difference time-domain simulation well. This kind of modulation of light has potential application in frequency conversion, compression, and widening of pulses of light. Some problems about experimental demonstration are discussed. Because of its concise form, the developed model can also be useful for studying other dynamic medium problems, for example, pulse shaping.

Analytical modelling of networks in multicomputer systems under bursty and batch arrival traffic

The hypercube and torus are two important message-passing network architectures of high-performance multicomputers. Analytical models of multicomputer networks under the non-bursty Poisson traffic have been widely reported. Motivated by the convincing evidence of bursty and batch arrival nature of traffic generated by many real-world parallel applications in high-performance computing environments, we develop a new and concise analytical model in this paper for hypercube and torus networks in the presence of batch message arrivals modelled by the compound Poisson process with geometrically distributed batch sizes. The average degree of virtual channel multiplexing is derived by employing a Markov chain which can capture the batch arrival nature. An attractive advantage of the model is its constant computation complexity independent of the network size. The accuracy of the analytical performance results is validated against those obtained from simulation experiments of an actual system.

Size-induced enhancement of chemical exchange saturation transfer (CEST) contrast in liposomes.

Liposome-based chemical exchange saturation transfer (lipoCEST) agents have shown great sensitivity and potential for molecular magnetic resonance imaging (MRI). Here we demonstrate that the size of liposomes can be exploited to enhance the lipoCEST contrast. A concise analytical model is developed to describe the contrast dependence on size for an ensemble of liposomes. The model attributes the increased lipoCEST contrast in smaller liposomes to their larger surface-to-volume ratio, causing an increased membrane water exchange rate. Experimentally measured rates correlate with size, in agreement with the model. The water permeability of liposomal membrane is found to be 1.11 +/- 0.14 microm/s for the specific lipid composition at 22 degrees C. Availability of the model allows rational design of the size of liposomes and quantification of their properties. These new theoretical and experimental tools are expected to benefit applications of liposomes to sensing the cellular environment, targeting and imaging biological processes, and optimizing drug delivery properties.

An analytical model for hypercubes in the presence of multiple time-scale bursty traffic

The interconnection network is one of the most critical architectural components in a parallel computer as any interaction between individual processors ultimately depends on its effectiveness. Recent studies have shown that traffic workloads in many parallel computation environments reveal burstiness over a number of time-scales, which has a considerable impact on network performance. Analytical modelling plays an important role in obtaining a clear understanding of the performance of interconnection networks with various design spaces and operating under different traffic conditions. This paper proposes a concise analytical model for the hypercube operating under multiple time-scale bursty traffic. The validity of the model is demonstrated by comparing analytical results to those obtained through simulation experiments of the actual system. The analytical model is then applied to evaluate the impact of multiple time-scale bursty traffic on the performance of hypercubes and investigate the effects of Hurst parameters of the traffic.

Concise Analytical Threshold Voltage Model for Cylindrical Fully Depleted Surrounding-Gate Metal–Oxide–Semiconductor Field Effect Transistors

On a basis of a quasi-2D potential analysis using the effective conducting path effect (ECPE), a concise analytical model for the threshold voltage in cylindrical fully depleted surrounding-gate (SG) metal–oxide–semiconductor field effect transistors (MOSFETs) is derived. With various depths of the effective conducting path, the minimum channel potential Φdeff,min induced by ECPE is used to develop the threshold voltage model. Besides the increased depth of the effective conducting path, a thin silicon body and a decreased oxide thickness can reduce threshold voltage roll-off simultaneously. It is also observed that the threshold voltage shift depends on the scaling factor. A large scaling factor is preferred to alleviate threshold voltage degradation. This paper not only provides a simple analytical model but also offers an efficient analysis of the threshold voltage of the short-channel cylindrical fully depleted SG MOSFETs.

Concise Analytical Model for Deep Submicron N-Channel Metal-Oxide-Semiconductor Devices with Consideration of Energy Transport

This paper reports a concise analytical model for deep submicron n-channel metal-oxide-semiconductor (NMOS) devices taking energy transport into consideration. It was verified that the I-V characteristics obtained using the analytical model agree with those obtained experimentally.

Synchrotron radiation intensity scaling with undulator errors

The author presents a concise analytical model which links the statistics of undulator field error to statistics of synchrotron radiation intensity. In particular, the author shows how undulator errors affect the phase of electron motion inside an undulator and express radiation intensity in terms of phase error statistics. Effects of trajectory and phase compensation are discussed. It is demonstrated that phase error is a more reliable descriptor of undulator quality than magnetic field error. The theory is directly applicable to synchrotron radiation devices and small-signal free-electron lasers (FELs), and can be also extended to strong-signal FELs. >