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EN
The study of the flow characteristics of the solid-fluid two phase flow in the cutter suction dredger is very important for exploring the slurry formation mechanism and optimizing the operational parameters. In this study, standard k-ε model and Multiple Reference Frame are applied to numerically simulate flow field in and around the cutting system, then with the steady convergent result of the simulation as the initial condition, Discrete Phase Mode is used to solve the particle motion equation by fully coupling the continuous phase and the particles . The influence of suction flow velocity and cutter’s rotating speed on particles suction are analyzed, and effectively suctioned particles numbers are also quantitatively studied. The simulation result shows that the DPM model is able to simulate the movement of particles in and around the cutter suction dredger’s cutting system, in the fluid flow filed velocity vector and pressure distribution on different planes show different characteristics, and under higher suction velocity and lower cutter rotating speed more particles are suctioned into the suction inlet. The results can help better understand flow characteristics of solidfluid 2-phase-flow of cutter suction dredger’s cutting system, and provide theoretical support for relative system design and operational parameters optimization.
EN
As the main predator and disperser of seeds, rodents play an important role in the process of vegetation regeneration by adopting different foraging and hoarding strategies in forest ecosystems. Infrared automated detection cameras and seed-tagging methods were used to understand the effects of rodents on seeds in natural environments. We chose the dominant species Apodemus peninsulae (Korean field mouse) as the focus of this study, and seeds of the three species Pinus koraiensis, Corylus mandshurica and Quercus mongolica were released and tracked in a temperate forest in northeast China. The results showed that approximately 80% of the seeds were manipulated by A. peninsulae, 15.1% of the seeds were used as food, 20.4% of the seeds were handled after feeding, 41.3% of the seeds were handled during storage, and 23.3% of the seeds remained intact. In addition, A. peninsulae preferred Q. mongolica (85.3%) and P. koraiensis (85.6%) over C. mandshurica (59.2%). The rodents frequently hoarded seeds from every species in many small, close-range, widely dispersed, single scatter-hoarded caches around the seed station. Most caches were dispersed approximately 2-4 m from the seed station. The results indicated that A. peninsulae adopted significant discriminatory processing strategies for predation, consumption, dispersal and hoarding of the different seeds of sympatric species. Seed size, proportion of kernel mass, nutrient content, and hull thickness characteristics affected the scatter-hoarding decision processes.
EN
In this work, an environmentally friendly type plasticizer was introduced. The synthesis consisted of two steps. In the first step, castor oil (CO) was acrylated and then the acrylated castor oil (ACO) was epoxidized with the presence of formic acid and hydrogen peroxide in the second step. The epoxidized acrylated castor oil (EACO) was characterized by FTIR and  1H-NMR techniques. The EACO was used as a main plasticizer to obtain plasticized PVC materials and compared with DOP. The results showed that EACO improved polyvinyl-chloride (PVC) plasticization performance and reduced Tg from 81.06°C to 1.40°C. Plasticized PVC materials with EACO showed similar mechanical properties and better thermal stability than DOP. EACO had better volatility stabilities, migration and solvent extraction in PVC than DOP. EACO can be used to replace DOP to prepare soft films.
EN
In order to provide a flexible access control in a secure manner in open networks, Attribute-Based Encryption (ABE) implements a fine-grained decentralized access control that is based on properties or attributes a user/node owns, which has paid more attention to the applications in large-scale and dynamic networks such as Mesh network, Wireless Body Area Networks (WBAN), and Internet of Things etc. However, as the openness and exposure in such networks, an attacker (e.g., virus, eavesdropper or sniffer) can blow the concrete implementation of cryptosystems, for example side channel attacks, and then obtains some sensitive and secret states in the system by monitoring pseudo-random numbers, internal results and secret keys and thus breaks the provable security of the systems. In this paper, in order to tolerate the possible key leakage, we model a fine-grained attribute revocable attribute-based encryption, namely ADR-lrABE, and then give the concrete construction, security analysis and resilient-leakage performance. The scheme tolerates the key of matching the challenge ciphertext to be partially revealed (i.e., key leakage resilience), and it provides a update mechanism to tolerate continual leakage that allows the attacker gains the leakage beyond the bound in the lifetime of the system (i.e., continual leakage tolerance). Also, it supports the properties of attribute direct revocation that the revocation procedure does not affect any other user’s secret key. That is, the proposed scheme is proven to be semantically secure even the decryption key is partially leaked to the attacker. We analyze the leakage-resilient performance of our scheme, and indicate that the scheme achieves approximate (82 + o(1)) fraction of the bits of a decryption key being leaked. We also provide a mechanism to transform the scheme into a prime-order group. To the best of our knowledge, our schemes are the first ABE that support attribute direct revocation mechanism in the presence of key leakage in noise channel or memory leakage environments.
5
Content available remote A New Approach to Security Analysis of Smart Home Authentication Systems
EN
ZigBee networks, with their characteristics of high availability, low power consumption and cost-effective devices, are perfectly appropriate to construct Wireless Sensor Networks (WSNs). Also, the natures of WSN listed above bring significant benefits over traditional communication networks used in smart home systems. A smart home system is meant to improve the quality of life through offering various automated, interactive and comfortable services, such as sensing and communicating the family member’s health information with their doctors, or remotely controlling the appliances via cellular phones, emails etc. These critical services make the security of personal privacy and the authority of control commands vital issues in Smart Home environments. While the smart home system suffer from many attacks, the security of the smart home system become an important and hard problem. And the authentication is the first parclose to the security of the system. However, according to our analysis, most system fail to achieve the authentication between the user and the device, Which leading to the compromise of the whole system. In this paper, we analyze the authentication challenges between the user the device in WSNs and in smart home Systems. To thoroughly detect, defense and foresee the authentication vulnerabilities existing in smart home networks, we proposed a security evaluation technique based on attack graph generation. We discuss the distinction between the attack graphs deployed in traditional networks and in smart home networks. Furthermore, we apply this technique into an experiment, and the results prove its practicality. And we then suggest a widely used protocol to the smart home authentication system.
EN
Propolis is a waxy substance produced by the honeybee that has been used as a form of traditional medicine and natural medicine since ancient times. Propolis has a wide spectrum of alleged applications, including potential anti-infection and anti-cancer effects. The following paper used a propolis extract containing 90% ethanol solution, 70% ethanol solution, ligarine, and dichloromethane as solvents that extracted the bioactive components. The highest yield of the propolis was obtained via the 70% ethanol leaching method and dichloromethane immersion stirring method. Fourier Transform Infrared (FTIR) analysis proved that the extracted propolis with dichloromethane had the highest methylene content and the maximum types of effective propolis components. A Propolis/PLA electrospinning solution was prepared by adding PLA powder into the supernatant of the dichloromethane-extract of propolis (DEP) directly, with there being no need for purification of the propolis extract and thus reducing the loss of active ingredients. DEP/PLA nanofiber was prepared via the electrospinning process, where it was found that with additional 4% PLA, the final electrospun fiber membrane was stabilised. tStudy of the antibacterial performance of the DEP/PLA electrospun membrane showed that the membrane affected some of the antibacterial properties. It was particularly effective when inhibiting Staphylococcus aureus, but not as effective when inhibiting Escherichia coli. This electrostatic spinning membrane could be used for food preservation, wound healing, and tissue engineering.
PL
Propolis to woskowa substancja wytwarzana przez pszczołę miodną, która od starożytności była stosowana jako forma tradycyjnej medycyny i medycyny naturalnej. Propolis ma szerokie spektrum domniemanych zastosowań, w tym potencjalne działanie przeciwinfekcyjne i przeciwnowotworowe. W pracy użyto ekstraktu propolisu zawierającego 90% roztwór etanolu, 70% roztwór etanolu, ligarinę i dichlorometan jako rozpuszczalniki, które ekstrahowały składniki bioaktywne. Najwyższą wydajność propolisu uzyskano metodą wymywania 70% etanolu i metodą mieszania zanurzeniowego w dichlorometanie. Analiza w podczerwieni z transformacją Fouriera (FTIR) wykazała, że wyekstrahowany propolis z dichlorometanem miał najwyższą zawartość metylenu i dużą skuteczność. Roztwór propolis/PLA przygotowano przez dodanie proszku PLA bezpośrednio do ekstraktu z dichlorometanu propolisu (DEP), bez potrzeby oczyszczania, tym sposobem zmniejszono utraty składników aktywnych. Nanowłókno DEP/PLA zostało przygotowane w procesie elektroprzędzenia, w którym stwierdzono, że przy 4% PLA membrana z włókien elektroprzędzonych jest stabilna. Ocena skuteczności antybakteryjnej membrany DEP/PLA wykazała, że posiada ona właściwości przeciwbakteryjne. Stwierdzono zadowalającą skuteczność w hamowaniu Staphylococcus aureus, przy jednocześnie niższej skuteczności w hamowaniu Escherichia coli. Wytworzona membrana może być używana do konserwacji żywności, gojenia się ran i w inżynierii tkankowej.
EN
Various additives, including cement, quicklime, fly ash, montmorillonite, sepiolite and their proportions were employed to stabilize/solidify artificially prepared soils contaminated simultaneously with two kinds of ions such as Cd2+ and Pb2+. The unconfined compressive strength of the stabilized soils was measured to estimate the possibility of recycling. The efficiency of Cd2+ and Pb2+ immobilization in contaminated soils was also evaluated using the US EPA TCLP toxicity test. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to elucidate the mechanisms responsible for the immobilization of heavy metals. The experimental results demonstrate that in terms of soils simultaneously polluted with Cd2+ and Pb2+ ions, the curing effect of fly ash is better than that of montmorillonite and sepiolite. When Cd2+ and Pb2+ coexist in soil specimens, the curing is more difficult than for Cd2+ or Pb2+ alone, which is antagonistic mechanism. Also, the leaching concentration of Cd2+ and Pb2+ gradually decreases upon increasing pH when pH < 8. For pH ≥ 8, the leaching concentration of Cd2+ and Pb2+ reached a minimum. Besides, the results of XRD and SEM are in agreement with those of the strength and leaching tests.
EN
In this work, an electromagnetic-mechanical-thermal coupling numerical model was proposed and electromagnetic riveting (EMR) experiments were performed using Φ6 mm TA1 titanium alloy rivets. Experimental verification showed that the proposed model could be suitable for predicting the EMR process, and the corresponding relationships among magnetic pressures, deformations of rivet tails and discharge voltages were revealed. In addition, simulation results presented that most deformations occurred in the locally upsetting stage of rivet tail. The maximum temperature rise reached up to 426 °C within the shear deformation zone of rivet tail. The rivet tails with high speed deformations could bear 9.9 kN shear loads and 12.5 kN pull-out loads, respectively. The EMR joining structures with multi-layered sheets had very high interference-fit qualities, and the average relative interferences were 2.5–3.0% for as-received multi-layered structures. Consequently, the EMR process can be used for difficult-to-deformation material rivets under the high efficiency, high quality and ambient temperature.
EN
Modified PVC (M-PVC) material with suppressed migration and low glass transition temperature was prepared via click reaction of a monooctyl phthalate derivative. Chemical structure and composition of M-PVC were characterized by FT-IR, 1H NMR and element analysis. Thermal stability, glass transition temperature and migration stability of M-PVC were studied with TGA, DSC and migration tests, respectively. The study showed that M-PVC exhibited poor thermal stability, and low glass transition temperature of 66.0°C. No migration was found in distilled water, 10% (v/v) ethanol, 30% (w/v)acetic acid and petroleum ether. The PVC material is expected to preparing PVC products in the areas with high migration resistance requirement.
EN
Swelling clay minerals, which are innately capable of dispersing into thin flakes in water, can significantly depress coal flotation. Some researchers partially attribute depression to pulp viscosity increments. This study sought to understand the role of swelling clay minerals in fine coal flotation, by investigating the rheological behavior of bentonite suspensions under controlled and uncontrolled dispersion conditions. The effect of collector, frother, and solution pH on rheological properties of the pulp was studied. Findings showed that at a natural pH, Newtonian flow properties were displayed when bentonite was directly added into a swelling suppressed solution containing calcium ions. The same process was repeated under uncontrolled conditions, and the suspensions transferred from Newtonian to non-Newtonian flows with pseudo-plastic characteristics, depending on the solid density. Further, pH value, methyl isobutyl carbinol (MIBC) and kerosene had the potential to alter the rheological behavior of controlled and uncontrolled systems, especially pH value in the uncontrolled system.
EN
We suggest to transfer the empirical downscaling methodology, which was developed mostly for atmospheric dynamics and impacts, to regional ocean problems. The major problem for doing so is the availability of decades-long and homogeneous and spatially detailed data sets. We have examined the performance of the STORM multidecadal simulation, which was run on a 0.1° grid and forced with 1950–2010 NCEP re-analyses, in the South China Sea and found the data suitable. For demonstration we build with this STORM-data downscaling model for the regional throughflow. The STORM data is compared with AVISO satellite observations and the ocean re-analysis dataset C-GLORS. We find the seasonal patterns and the inter-annual variability of sea surface height anomaly in both the C-GLORS data and the STORM simulation consistent with the AVISO-satellite data. Also the strong westward intensification and the seasonal patterns of South China Sea circulation steered by the monsoon have been presented well. As an important indicator of vertical movement, the sea surface temperature distribution maps are also very close, especially for the narrow upwelling region in summer. We conclude that the output of the STORM simulation is realistically capturing both the large-scale as well as the small-scale dynamical features in the South China Sea.
EN
Hydrofoil is widely used in underwater vehicle for the excellent hydrodynamic characteristics. Currently, researches are mostly about the rigid hydrofoil while the flexible hydrofoil, like the caudal fin, has not been studied adequately. In this paper, the fish was regarded as the bionic object. Then the kinematics model to describe the fish swimming was put forward. A fin-peduncle propulsion mechanism was designed based on the kinematics model to achieve the similar sine curve swimming model. The propulsion mechanism was optimized by Matlab to reduc the deviation between the output curve of the fin-peduncle propulsion mechanism and the ideal motion trajectory. Moreover, the motion phase angles among flexible articulations are optimized to reduce fluid resistance and improve propulsive efficiency. Finally, the fish-like hydrofoil oscillation is simulated by fluid-solid coupling method based on the Fluent. It was shown that the optimized flexible fish-like oscillation could generate the motion that follows the similar law of sine. The propulsive efficiency of oscillating hydrofoil propeller is much higher than that of the screw propeller, and the flexible oscillation has higher propulsive efficiency than the rigid oscillation without obvious fluid resistance increase.
EN
In this study, palm oil was the first time to convert into a novel polyester plasticizer for polyvinyl chloride (PVC). In the first stage, palm oil was converted into palm oil monoglyceride (POM) by alcoholysis with glycerol. Next, a novel palm oil monoglycerides based polyester plasticizer (POMP) was synthesized from POM and maleic anhydride through esterification and condensation reaction. The structure of POMP was characterized with FTIR, 1H NMR and GPC. Then PVC blends were prepared using POMP as a plasticizer, melting behavior, thermal property, compatibility, mechanical properties and mechanism of plasticization of PVC blends were systematically studied. Melting behavior indicated that POMP could decrease the torque and the melt viscosity of PVC blends that was conducive to process. With the content of POMP increasing from 5 g to 15 g in PVC blends, the plasticized PVC blends demonstrated better compatibility, the degradation temperature (Td) increased from 252.6°C to 257.0°C, the glass transition temperature (Tg) decreased from 55°C to 49.5°C. Plasticization was put into effect by interaction of the electron cloud between the PVC chain and POMP molecule. This study may lead to the development of new type of PVC plasticizer based on vegetable oil.
EN
Purpose: This study is to reveal the deformation of intervertebral disc (IVD), the stress distribution of solid phase and liquid phase, the variation of fluid flux and flow velocity in lumbar spine and the influence of different permeability parameters on them under intermittent compressive loading. Methods: A poroelastic FEM of L4-L5 is assigned with different permeability parameters to analyze the deformation, stress distribution and fluid convection under intermittent compressive loads. Results: The results show that the pore pressure of IVD decreases with time, but the effective stress increases under intermittent compressive loads. The axial and radial strain will increase and fluid loss will recover at a more rapid rate if the permeability of endplate increases during unloading period. The velocity vectors show that most of the liquid in the disc flows into vertebrae through endplates and only a small quantity of liquid flows through the annulus fibrosus at the loading step, however, at the unloading step, almost all the liquid flowing into IVD is through the endplates. Conclusions: The changing rate of pore pressure and effective stresses of nucleus pulposus and annulus fibrosus with higher permeability is smaller than that with smaller permeability. The degenerated endplate (with low permeability) yields high flow velocity decreasing gradient, which might impede liquid inflowing/outflowing smoothly through the endplates. The fluid flowing velocity in loading phase is faster than that in unloading phase, so a short resting time can relieve fatigue, but could not recover to the original liquid condition in IVDs.
EN
Poly(vinyl alcohol) films were prepared with manganous chloride (MnCl2 · 4H2O) and glycerin as complex plasticizer. The micro morphology of pure PVA film and complex plasticizer plasticized PVA films was observed by scanning electron microscope (SEM). The interaction between complex plasticizer and PVA molecules was investigated by Fourier transform infrared spectroscopy (FT-IR). The influence of complex plasticizer on crystalline, thermal and mechanical properties of PVA films was studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TG), and tensile testing, respectively. The results showed that the complex plasticizer of MnCl2 · 4H2O/glycerin could interacted with PVA molecular and then effectively destroy the crystals of PVA. PVA films plasticized with complex plasticizer of MnCl2 · 4H2O/glycerin became soft and ductile, with lower tensile strength and higher elongation at break compared with PVA films. This is an important cause of plasticization of the complex plasticizer of MnCl2 · 4H2O/glycerin on PVA films.
EN
The metal-organic framework (MOF) is a kind of new type self-assembly porous coordination polymer, which possesses many characteristics such as homologic hole, controllable size of cave, high specific surface area, and good chemical stability. In this study, a three-dimensional framework [Zn2(d-Cam)2(4,4′-bpy)]n with large homochiral channel and the orderly arrangement of left- and right-handed helices was used as chiral stationary phases (CSPs) in gas chromatography (GC). [Zn2(d-Cam)2 (4,4′-bpy)]n-coated open tubular column was prepared by a dynamic coating method for high-resolution GC. Some racemates, isomers, linear alkanes, and alcohols are used as the targets for separation. The column coating properties efficiency, polarity, and selectivity were studied. The experimental results show that the stationary phase has outstanding selectivity and also possesses good recognition ability toward these compounds.
EN
This paper describes the design and test of a new high-current electronic current transformer based on a Rogowski coil. For better performances, electronic current transformers are used to replace conventional electro-magnetic inductive current transformers based on ferromagnetic cores and windings to measure high-current on the high voltage distribution grids. The design of a new high-current electronic current transformer is described in this paper. The principal schemes of the prototype and partial evaluation results are presented. Through relative tests it is known that the prototype has a wide dynamic range and frequency band, and it can allow high accuracy measurements.
EN
Electronic voltage transformers (EVT) and electronic current transformers (ECT) are important instruments in a digital substation. For simple, rapid and convenient development, the paper proposed an on-site calibration system for electronic instrument transformers based on LabVIEW. In the system, analog signal sampling precision and dynamic range are guaranteed by the Agilent 3458A digital multimeter, and data synchronization is also achieved based on a self-developed PCI synchronization card. To improve the measurement accuracy, an error correction algorithm based on the Hanning window interpolation FFT has good suppression of frequency fluctuation and inter-harmonics interference. The human-computer interface and analysis algorithm are designed based on LabVIEW, and the adaptive communication technology is designed based on IEC61850 9-1/2. The calibration system can take into account pairs of digital output and analog output of the electronic voltage/current transformer calibration. The results of system tests show that the calibration system can meet the requirements of 0.2 class calibration accuracy, and the actual type test and on-site calibration also show that the system is easy to operate with convenience and satisfactory stability.
EN
Automated Incident Detection (AID) is an important part of Advanced Traffic Management and Information Systems (ATMISs). An automated incident detection system can effectively provide information on an incident, which can help initiate the required measure to reduce the influence of the incident. To accurately detect incidents in expressways, a Support Vector Machine (SVM) is used in this paper. Since the selection of optimal parameters for the SVM can improve prediction accuracy, the tabu search algorithm is employed to optimize the SVM parameters. The proposed model is evaluated with data for two freeways in China. The results show that the tabu search algorithm can effectively provide better parameter values for the SVM, and SVM models outperform Artificial Neural Networks (ANNs) in freeway incident detection.
20
Content available remote Quantitative Analysis of Lattice-valued Kripke Structures
EN
To model and analyze systems with multi-valued information, in this paper, we present an extension of Kripke structures in the framework of complete residuted lattices, which we will refer to as lattice-valued Kripke structures (LKSs). We then show how the traditional trace containment and equivalence relations, can be lifted to the lattice-valued setting, and we introduce two families of lattice-valued versions of the relations. Further, we explore some interesting properties of these relations. Finally, we provide logical characterizations of our relations by a natural extension of linear temporal logic.
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