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991.
992.
993.
Hamid Chakeri Rohola Hasanpour Mehmet Ali Hindistan Bahtiyar Ünver 《Bulletin of Engineering Geology and the Environment》2011,70(3):439-448
Tunnels are increasingly being excavated in soft ground conditions when services are required in urban environments, and it
is now common to have tunnels crossing at various elevations. As the tunnel excavations are undertaken at different levels,
there will be an interaction which can have a significant influence on stress distributions and consequently deformations
within the tunnels and surface settlement. As multi-layer tunnelling is a three dimensional phenomenon in nature, 3D numerical
solutions must be utilized for perpendicularly crossing tunnels at various levels. This paper reports the investigations into
the changes in stress distribution, deformations and surface settlements which may be expected when the twin Tohid Tunnels
pass beneath the Line 4 metro tunnel in Tehran. 相似文献
994.
Temporal fluctuations of the speckle pattern formed upon backscattering of a laser beam from an interface between gold and nonlinear polymer film have been observed as a function of optical power. The instability can be explained by coupling of laser light to surface plasmons and other guided modes, which experience multiple scattering while propagating in the film along the interface. The speckle pattern produced in this process is extremely sensitive to fluctuations of the scattering potential near the interface. 相似文献
995.
Ayesha Binte Ashfaq Muhammad Qasim Ali Syed Ali Khayam 《Journal in Computer Virology》2011,7(1):63-81
An unprecedented growth in computer and communication systems in the last two decades has resulted in a proportional increase
in the number and sophistication of network attacks. In particular, the number of previously-unseen attacks has increased
exponentially in the last few years. Due to the rapidly evolving nature of network attacks, a considerable paradigm shift
has taken place in the intrusion detection community. The main focus is now on Network Anomaly Detection Systems (NADSs) which
model and flag deviations from normal/benign behavior of a network and can hence detect previously-unseen attacks. Contemporary
NADS borrow concepts from a variety of theoretical fields (e.g., Information theory, stochastic and machine learning, signal
processing, etc.) to model benign behavior. These NADSs, however, fall short of achieving acceptable performance levels as
therefore widespread commercial deployments. Thus, in this paper, we firstly evaluate the performance of eight prominent network-based
anomaly detectors under malicious portscan attacks to identify which NADSs perform better than others and why. These NADSs
are evaluated on three criteria: accuracy (ROC curves), scalability (with respect to varying normal and attack traffic rates,
and deployment points) and detection delay. These criteria are evaluated using two independently collected datasets with complementary
strengths. We then propose novel methods and promising guidelines to improve the accuracy and scalability of existing and
future anomaly detectors. Experimental analysis of the proposed guidelines is also presented for the proof of concept. 相似文献
996.
In this paper, an adaptive control scheme, based on fuzzy logic systems, for pH control is addressed. For implementation of the proposed scheme no composition measurement is required. Stability of the closed-loop system is established and it is shown that the solution of the closed-loop system is uniformly ultimately bounded and under a certain condition, asymptotical stability is achieved. Effectiveness of the proposed controller is tested through simulation and experimental studies. Results indicate that the proposed controller has good performances in set-point tracking and load rejection and much better than that of a tuned PI controller. 相似文献
997.
Organizations, such as federally-funded medical research centers, must share de-identified data on their consumers to publicly accessible repositories to adhere to regulatory requirements. Many repositories are managed by third-parties and it is often unknown if records received from disparate organizations correspond to the same individual. Failure to resolve this issue can lead to biased (e.g., double counting of identical records) and underpowered (e.g., unlinked records of different data types) investigations. In this paper, we present a secure multiparty computation protocol that enables record joins via consumers’ encrypted identifiers. Our solution is more practical than prior secure join models in that data holders need to interact with the third party one time per data submission. Though technically feasible, the speed of the basic protocol scales quadratically with the number of records. Thus, we introduce an extended version of our protocol in which data holders append k-anonymous features of their consumers to their encrypted submissions. These features facilitate a more efficient join computation, while providing a formal guarantee that each record is linkable to no less than k individuals in the union of all organizations’ consumers. Beyond a theoretical treatment of the problem, we provide an extensive experimental investigation with data derived from the US Census to illustrate the significant gains in efficiency such an approach can achieve. 相似文献
998.
999.
Moez Smaoui Zoubeir Bouaziz Ali Zghal Gilles Dessein Maher Baili 《The International Journal of Advanced Manufacturing Technology》2011,56(5-8):463-474
Since industry is rapidly developing, either locally or globally, manufacturers witness harder challenges due to the growing competitivity. This urges them to better consider the four factors linked to production and output: quality, quantity, cost and price, quality being of course the most important factor which constitutes their main concern. Efforts will be concentrated??in this research??on improving the quality and securing more accuracy for a machined surface in ball-end milling. Quality and precision are two essential criteria in industrial milling. However, milling errors and imperfections, due mainly to the cutting tool deflection, hinder the full achieving of these targets. Our task, all along this paper, consists in studying and realizing the simulation of the deflected cutting tool trajectory, by using the methods which are available. In a future stage, and in the frame of a deeper research, the simulation process will help to carry out the correction and the compensation of the errors resulting from the tool deflection. The corrected trajectory which is obtained by the method mirror will be sent to the machine. To achieve this goal, the next process consists??as a first step??in selecting a model of cutting forces for a ball-end mill. This allows to define??later on??the behavior of this tool, and the emergence of three methods namely the analytical model, the finite elements method, and the experimental method. It is possible to tackle the cutting forces simulation, all along the tool trajectory, while this latter is carrying out the sweeping of the part to be machined in milling and taking into consideration the cutting conditions, as well as the geography of the workpiece. A simulation of the deflected cutting tool trajectory dependent on the cutting forces has been realized. 相似文献
1000.
In this study, NiCu composite coating was electrochemically deposited on a copper electrode (Cu/NiCu) and tested for hydrogen evolution reaction (HER) in 1 M KOH solution for long-term electrolysis with the help of cathodic current–potential curves and electrochemical impedance spectroscopy (EIS) techniques. The bulk and surface composition of the coating was determined using atomic absorption spectroscopy (AAS) and energy dispersive X-ray (EDX) analysis. The surface morphology was investigated by scanning electron microscopy (SEM). The effect of electrolysis on the corrosion behavior of the Cu/NiCu electrode was also reported. It was found that the NiCu coating had a compact and porous structure with good time stability. The HER activity of the coating was stable over 120 h electrolysis and the HER mechanism was not modified during the operation. The corrosion tests showed that the corrosion resistance of the Cu/NiCu electrode changed when a cathodic current was applied to the electrolysis system. 相似文献