综合资源展示 综合资源展示

最小化 最大化

1 Performance and mechanism of an innovative humidity-controlled hot-air drying method for concentrated starch gels: A case of sweet potato starch noodles 2018-07-05             

HTML   |   详细信息   |  

Publication date: 15 December 2018
Source:Food Chemistry, Volume 269

Author(s): Zhuoya Xiang, Fayin Ye, Yun Zhou, Lei Wang, Guohua Zhao

The effects of humidity control on dried starch gels were investigated using starch noodles as a model. A two-stage innovative hot-air-drying regime was developed with the first stage humidity-controlled (70 °C, 60% RH) and the second at high temperature (100 °C). The proposed drying method is comparable to natural-air-drying in product quality and to conventional hot-air-drying (70 °C) in production efficiency. The operating humidity of the first stage predominated the swelling index and rehydration ratio of dry noodles as well as the hardness and chewiness of cooked noodles. The results from XRD, DSC, SEM, digital microscopy and low field TD 1H NMR evidenced that these outcomes were largely ascribed to the higher shrinkage, lower porosity, smoother surface, lesser shape deformation and higher starch retrogradation resulting from increased humidity. The results reported herein are valuable for regulating the physicochemical properties of dried starch gels and glimpsing the underlying mechanisms of related operations.

2 NMR Spectroscopy Techniques: Hyperpolarization for Sensitivity Enhancement 2018-07-05             

HTML   |   详细信息   |  

Publication date: 2018
Source:Reference Module in Chemistry, Molecular Sciences and Chemical Engineering

Author(s): Boyd M. Goodson, Bryce Kidd, Jan-Bernd Hövener, Leif Schröder, Thomas Theis, Nicholas Whiting, Eduard Y. Chekmenev

Nuclear spin polarization can be significantly enhanced through a process called hyperpolarization, resulting in up to several orders increase of the nuclear spin polarization (compared to equilibrium thermal polarization) with concomitant gains in NMR spectroscopic and imaging signals. Here, we describe the leading techniques for NMR hyperpolarization: dynamic nuclear polarization (DNP), spin exchange optical pumping (SEOP), parahydrogen induced polarization (PHIP), and signal amplification by reversible exchange (SABRE). We also discuss key features of and schemes associated with NMR spectroscopic detection in the context of NMR hyperpolarization applications.

3 An adaptive control momentum method as an optimizer in the cloud 2018-07-05             

HTML   |   详细信息   |  

Publication date: December 2018
Source:Future Generation Computer Systems, Volume 89

Author(s): Jianhao Ding, Lansheng Han, Dan Li

Many issues in the cloud can be transformed into optimization problems, where data is of high dimension and randomness. Thus, stochastic optimizing is a key to Autonomous Cloud. And one of the most significant discussions in this field is how to adapt the learning rate and convergent path dynamically. This paper proposes a gradient-based algorithm called Adacom, that is based on an adaptive control system and momentum. Critically inheriting the previous studies, a reference model is introduced to generate the update. The method reduces noise and decides on paths with less oscillation, while maintaining the accumulated learning rate. Due to system design properties, the method requires fewer hyper-parameters for tuning. We state the prospect of Adacom as a general optimizer in Autonomous Cloud, and explore the potential of Adacom for pervasive computing by the assumption of transition data. Then we demonstrate the convergence of Adacom theoretically. The evaluations over the simulated transition data prove the feasibility and superiority of Adacom with other gradient-based methods.

4 On the contact interaction of a two-layer beam structure with clearance described by kinematic models of the first, second and third order approximation 2018-07-01             

HTML   |   详细信息   |  

Publication date: 15 January 2019
Source:Mechanical Systems and Signal Processing, Volume 115

Author(s): V.A. Krysko, J. Awrejcewicz, O.A. Saltykova, I.V. Papkova, A.V. Krysko

In this article, the contact interaction of two geometrically non-linear beams with a small clearance is studied by employing various approximations of the kinematic beam models. Our investigation concerns two-case studies, i.e. when the upper beam is governed by the second order Timoshenko model (i) or by third order Pelekh-Sheremetev-Reddy-Levinson model (ii), whereas in both cases the lower beam is described by the kinematic (Bernoulli-Euler) model of the first approximation. The upper beam is subjected to the transversal, uniformly distributed harmonic load, whereas the beam interaction follows the classical Kantor’s model. The problem is highly non-linear due to occurrence of the geometric von Kármán non-linearity and the contact interaction between beams (structural non-linearity). The governing PDEs are reduced to ODEs by the method of finite differences (FDM) of the second order. The obtained ODEs are solved by a few Runge-Kutta type methods of different orders. Results of convergence versus the number of partition points along the spatial co-ordinate and time steps are investigated. New non-linear phenomena of the studied structural package are detected, illustrated and discussed with emphasis on the “true” chaotic vibrations. In particular, three qualitatively different algorithms for computation of largest Lyapunov exponents are employed, and the differences between geometrically linear versus non-linear problems are reported.

5 Model recovery for Hammerstein systems using the hierarchical orthogonal matching pursuit method 2018-07-01             

HTML   |   详细信息   |  

Publication date: 1 January 2019
Source:Journal of Computational and Applied Mathematics, Volume 345

Author(s): Dongqing Wang, Yaru Yan, Yanjun Liu, Junhang Ding

Most papers concentrate on the parameter identification of Hammerstein systems with known orders. This paper, motivated by the recent developments in sparse approximations, investigates the combined parameter and order determination of Hammerstein systems. The methodology used relies on greedy schemes—the orthogonal matching pursuit (OMP) algorithm in the compressive sensor (CS) theory. In particular, the first step recasts a bilinear Hammerstein system into two fictitious pseudo-regressive sub-systems which respectively contain the parameters of the nonlinear part or the parameters of the linear part by the hierarchical identification principle. The second step adopts a hierarchical orthogonal matching pursuit (H-OMP) selection procedure to interactively select the parameters and orders of the two sub-systems under the frame of the compressive sensor. Finally, the proposed algorithm is tested on a simulation example.

6 Toward a smart data transfer node 2018-06-28             

HTML   |   详细信息   |  

Publication date: December 2018
Source:Future Generation Computer Systems, Volume 89

Author(s): Zhengchun Liu, Rajkumar Kettimuthu, Ian Foster, Peter H. Beckman

Scientific computing systems are becoming significantly more complex, with distributed teams and complex workflows spanning resources from telescopes and light sources to fast networks and Internet of Things sensor systems. In such settings, no single, centralized administrative team and software stack can coordinate and manage all resources used by a single application. Indeed, we have reached a critical limit in manageability using current human-in-the-loop techniques. We therefore argue that resources must begin to respond automatically, adapting and tuning their behavior in response to observed properties of scientific workflows. Over time, machine learning methods can be used to identify effective strategies for autonomic, goal-driven management behaviors that can be applied end-to-end across the scientific computing landscape. Using the data transfer nodes that are widely deployed in modern research networks as an example, we explore the architecture, methods, and algorithms needed for a smart data transfer node to support future scientific computing systems that self-tune and self-manage.

7 System based on thermal control of the HCCI technology developed for reduction of the vehicle NOX emissions in order to fulfil the future standard Euro 7 2018-06-27             

HTML   |   详细信息   |  

Publication date: 1 December 2018
Source:Science of The Total Environment, Volume 643

Author(s): Michal Puškár, Melichar Kopas

On the present the environmental protection belongs among the most important worldwide priorities. From this reason there is valid within the framework of the European Union the standard Euro, which is specifically defined in the transport area. Nowadays the actual issue of this standard is signed Euro 6. It is established in order to eliminate most of the undesirable air pollutants. However, there is already prepared a new and even stricter emission standard Euro 7. It is a well-known fact that the actual emission standards are very hard and the automobile factories, together with the engine design concepts are trying to fulfil the new emission standards, mainly the NOX emission requirements. These circumstances also caused the infamous affair “dieselgate”. The new engine concept, which is called HCCI (Homogeneous Charge Compression Ignition), could be a suitable solution of the present NOX emission problems. Principle of the HCCI technology is based on self-ignition of the homogenous fuel mixture using compression in order to reduce emissions, whereas the NOX emission level is almost negligible. However, there are also several essential problems connected with the above-mentioned innovative technology, for example a high level of pressures arising during the compression process and intensive heat release. Another serious problem is a complicated control of the self-ignition process. This article presents an original technical solution, which enables to regulate the whole self-ignition process and in this way to ensure a reliable operation of the HCCI engine. We would like to emphasize also a fact that this unique solution was applied for a patent, as well. The innovated piston combustion engine was installed in the experimental vehicle designed for participation at the international competition shell eco marathon 2018 in London focused on minimisation of the fuel consumption.

Graphical abstract


8 Quantifying the differences in structure and mechanical response of confectionery products resulting from the baking and extrusion processes 2018-06-23             

HTML   |   详细信息   |  

Publication date: December 2018
Source:Journal of Food Engineering, Volume 238

Author(s): Saba S. Butt, Idris K. Mohammed, Vivek Raghavan, James Osborne, Hugh Powell, Maria N. Charalambides

Extrusion has potential advantages over baking in terms of throughput, asset cost and flexibility. However, it is challenging to achieve through extrusion the “light, crispy” texture of a more traditional baked confectionery. This study compares and contrasts for the first time confectionery products produced through these two processes, i.e. baking and extrusion. The microstructural differences are measured using imaging techniques, i.e. Scanning Electron Microscopy (SEM) and X-Ray Tomography (XRT) whereas mechanical characterisation is used to highlight differences in the resulting mechanical properties. Crucial information is presented which shows that the two technologies result in different mechanical properties and microstructures, even if the level of porosity in the two products is kept constant. In addition, confectionery products whether they are produced through baking or extrusion, have irregular geometries. The latter makes mechanical characterisation a real challenge. Therefore this study also presents rigorous methods for measuring true mechanical properties such that meaningful and valid comparisons may be made. The accuracy of the chosen methodologies is verified through experiments using flat and tubular extruded geometries as well as testing the products in various directions. It was concluded that the manufacturing method and, in the case of extrusion, the initial moisture content influences the microstructure and mechanics of confectionery products, both of which have an impact on consumer sensory perception.

9 Localization of dynamic forces on structures with an interior point method using group sparsity 2018-06-23             

HTML   |   详细信息   |  

Publication date: 15 January 2019
Source:Mechanical Systems and Signal Processing, Volume 115

Author(s): J. Wambacq, K. Maes, A. Rezayat, P. Guillaume, G. Lombaert

This paper presents an algorithm for the localization of forces applied to a structure. The force estimation is performed in the frequency domain based on a limited number of sensors and a linear dynamic system model and it involves minimizing an objective function penalized with a group sparsity term. The minimization of this objective function is formulated as a second order cone program, which is solved using an interior point method. This allows for a reduction of the calculation time when compared to other algorithms that are currently available to enforce group sparsity on the forces, especially for large scale problems. The presented algorithm is first verified using numerical simulations. Next, a validation is performed using data obtained from a field test on a footbridge, where two locations on the bridge deck are excited using hammer impacts and the force localization is performed assuming a total of 108 possible force locations.

10 Correlation of Regional Lung Ventilation and Gas Transfer to Red Blood Cells: Implications for Functional-Avoidance Radiation Therapy Planning 2018-06-21             

HTML   |   详细信息   |  

Publication date: Available online 14 April 2018
Source:International Journal of Radiation Oncology*Biology*Physics

Author(s): Leith J. Rankine, Ziyi Wang, Bastiaan Driehuys, Lawrence B. Marks, Chris R. Kelsey, Shiva K. Das

Purpose To investigate the degree to which lung ventilation and gas exchange are regionally correlated, using the emerging technology of hyperpolarized (HP)-129Xe magnetic resonance imaging (MRI). Methods and Materials Hyperpolarized-129Xe MRI studies were performed on 17 institutional review board–approved human subjects, including 13 healthy volunteers, 1 emphysema patient, and 3 non-small cell lung cancer patients imaged before and approximately 11 weeks after radiation therapy (RT). Subjects inhaled 1 L of HP-129Xe mixture, followed by the acquisition of interleaved ventilation and gas exchange images, from which maps were obtained of the relative HP-129Xe distribution in three states: (1) gaseous, in lung airspaces; (2) dissolved interstitially, in alveolar barrier tissue; and (3) transferred to red blood cells (RBCs), in the capillary vasculature. The relative spatial distributions of HP-129Xe in airspaces (regional ventilation) and RBCs (regional gas transfer) were compared. Further, we investigated the degree to which ventilation and RBC transfer images identified similar functional regions of interest (ROIs) suitable for functionally guided RT. For the RT patients, both ventilation and RBC functional images were used to calculate differences in the lung dose–function histogram and functional effective uniform dose. Results The correlation of ventilation and RBC transfer was ρ = 0.39 ± 0.15 in healthy volunteers. For the RT patients, this correlation was ρ = 0.53 ± 0.02 before treatment and ρ = 0.39 ± 0.07 after treatment; for the emphysema patient it was ρ = 0.24. Comparing functional ROIs, ventilation and RBC transfer demonstrated poor spatial agreement: Dice similarity coefficient = 0.50 ± 0.07 and 0.26 ± 0.12 for the highest-33%- and highest-10%-function ROIs in healthy volunteers, and in RT patients (before treatment) these were 0.58 ± 0.04 and 0.40 ± 0.04. The average magnitude of the differences between RBC- and ventilation-derived functional effective uniform dose, fV20Gy, fV10Gy, and fV5Gy were 1.5 ± 1.4 Gy, 4.1% ± 3.8%, 5.0% ± 3.8%, and 5.3% ± 3.9%, respectively. Conclusion Ventilation may not be an effective surrogate for true regional lung function for all patients.

共计:2271条记录 页次:1/228    下一页 末页   跳转到第 页  
您还没有登录。 请先登录再使用本系统。
您还没有登录。 请先登录再使用本系统。