Search

Virtual assembly technology has been widely used in the fields of mechanical equipment and industrial simulations. However, the current virtual assembly is mainly centered on function and technology, without considering human interaction experience. Aiming at the realization, analysis and display of virtual assembly of large and complex mechanical structure, a complete set of technical solutions is introduced. 3D model establishment and assembly animation simulation are carried out based on UG and Tecnomatix platforms; Through VR technology, a human-computer interaction mode for structure-oriented virtual assembly process is built, which enables users to simulate the operations of assembly objects; Shutter 3D technology is used to output the experience picture of a single user in VR through a high-definition 3D projector, which can satisfy the immersive experience of multiple users in the 3D virtual assembly process at the same time. This technical route has a positive significance for simulating the assembly process of large complex mechanical structures more truly, verifying and improving the assembly scheme, and realizing the human-computer interaction oriented to the assembly process. [ABSTRACT FROM AUTHOR]

The emerging volumetric videos offer a fully immersive, six degrees of freedom (6DoF) viewing experience, at the cost of extremely high bandwidth demand. In this paper, we design, implement, and evaluate Vues, an edge-assisted transcoding system that delivers high-quality volumetric videos with low bandwidth requirement, low decoding overhead, and high quality of experience (QoE) on mobile devices. Through an IRB-approved user study, we build a first-of-its-kind QoE model to quantify the impact of various factors introduced by transcoding volumetric content into 2D videos. Motivated by the key observations from this user study, Vues employs a novel multiview approach with the overarching goal of boosting QoE. The Vues edge server adaptively transcodes a volumetric video frame into multiple 2D views with the help of a few lightweight machine learning models and strategically balances the extra bandwidth consumption of additional views and the improved QoE, indicated by our QoE model. The client selects the view that optimizes the QoE among the delivered candidates for display. Comprehensive evaluations using a prototype implementation indicate that Vues dramatically outperforms existing approaches. On average, it improves the QoE by 35% (up to 85%), compared to single-view transcoding schemes, and reduces the bandwidth consumption by 95%, compared to the state-of-the-art that directly streams volumetric videos. [ABSTRACT FROM AUTHOR]

Foodborne disease is a growing public health problem worldwide and imposes a considerable economic burden on hospitals and other healthcare costs. Thus, accurately predicting the propagation of foodborne disease is crucial in preventing foodborne disease outbreaks. Few studies have investigated the dependencies between environmental variables and foodborne disease activity. This study develops a regularization-based eXtreme gradient boosting approach for foodborne disease trend forecasting considering environmental effects to capture dependencies hidden in foodborne disease time series. A real case in Shanghai, China was studied to validate our proposed model along with comparisons to traditional and benchmark algorithms for foodborne disease prediction. Results show that the foodborne disease prediction approach we propose achieves slightly superior performance in terms of one-day-ahead prediction of foodborne disease, and presents more robust prediction for 27 days ahead prediction. [ABSTRACT FROM AUTHOR]

To understand the effect of surface evaporation of water on thermocapillary convection in annular pool under the pure steam environment, we performed a series of three-dimensional numerical simulations by using the finite volume method based on the statistical evaporation rate theory. Prandtl number of water is 6.13. Results show that due to the latent heat absorbed as a result of evaporation, the radial temperature gradient on the free surface near the outer cylinder increases, which leads to the increase of the thermocapillary force near the outer cylinder. Flow pattern depends slightly on Marangoni number. But with the increase of Marangoni number, the flow is enhanced and the flow cell near the outer cylinder gradually expands to the middle of the annular pool. With the increase of the aspect ratio, thermocapillary convection is enhanced and the evaporation strengthens. [ABSTRACT FROM AUTHOR]

In digital circuit designs, sequential components such as flip-flops are used to synchronize signal propagations. Logic computations are aligned at and thus isolated by flip-flop stages. Although this fully synchronous style can reduce design efforts significantly, it may affect circuit performance negatively, because sequential components can only introduce delays into signal propagations instead of accelerating them. In this paper, we propose a new timing model, VirtualSync, in which signals, specially those along critical paths, are allowed to propagate through several sequential stages without flip-flops. Timing constraints are still satisfied at the boundary of the optimized circuit to maintain a consistent interface with existing designs. By removing clock-to-q delays and setup time requirements of flip-flops on critical paths, the performance of a circuit can be pushed even beyond the limit of traditional sequential designs. Experimental results demonstrate that circuit performance can be improved by up to 11.5% (average 3.1%) compared with that after thorough sizing and retiming, while the increase of area is still negligible. [ABSTRACT FROM AUTHOR]

AHP method for weight calculation method, will introduce the subjective concept of "experts, supposed steps", for the objective result has certain uncertainty, causes the classroom interaction data attribute weights proportion difference is not big, the whole class achievement trend of convergence, introduce the concept of Apriori-AHP. C4.5 is used to calculate the weight of attribute column, and then using the Apriori-AHP algorithm calculate attribute weights, attribute importance weights on judgment performance indicators table overall consideration, with the weight of index table of gifted student achievement, make the class performance trends to fluctuate, have tended to be "standard" real results for teacher reference. [ABSTRACT FROM AUTHOR]

With the rapid development of Internet and the extensive application of computer technology, the security of information becomes more and more serious, and the information security technology with data encryption technology as the core has also been developed greatly. Data encryption technology not only can encrypt and decrypt data, but also can realize digital signature, authentication and authentication and other functions, thus ensuring the confidentiality, integrity and confirmation of data transmission over the network. In order to improve the security of data in network communication, in this paper, a hybrid encryption system is used to encrypt and decrypt the triple DES algorithm with high security, and the two keys are encrypted with RSA algorithm, thus ensuring the security of the triple DES key and solving the problem of key management; At the same time to realize digital signature using Java security software, to ensure data integrity and non-repudiation. Finally, the data encryption system is developed by Java language. The data encryption system is simple and effective, with good security and practicality. [ABSTRACT FROM AUTHOR]

Atom Interferometry is proved to be a potential method for measuring the acceleration of atoms due to Gravity, we are now building a feasible system of cold atom gravimeter. In this paper development and the important applications of laser cooling and trapping atoms are introduced, some key techniques which are used to obtain 87Rb cold atoms in our experiments are also discussed. [ABSTRACT FROM AUTHOR]

Dynamic torque calibration method based on rotating table and interferometric system is studied in this paper. A load mass with certain moment of inertia are screwed on the top of torque transducer, the dynamic torque is realized by load object are traceable to angular acceleration and moment of inertia of the object by M(t) = IӪ(t), where I is the total moment of inertia acting on the sensing element of the torque transducer and Ӫ is the time and spatial-dependent angular acceleration of the load object which is directly measured by a laser interferometer. This paper will introduce a dynamic torque calibration system developed at Changcheng Institute of Metrology and Measurement (CIMM). It uses servomotor to generate dynamic torque in the range from 0.1Nm to 200Nm, and heterodyne laser interferometers cooperated with column grating are used for angular acceleration measurement. An airbearing system is developed to increase the performance of the dynamic turque calibration system. This paper introduce the setup of the dynamic torque calibration system. [ABSTRACT FROM AUTHOR]

At nanometer manufacturing technology nodes, process variations significantly a ect circuit performance. To combat them, post-silicon clock tuning buffers can be deployed to balance timing budgets of critical paths for each individual chip after manufacturing. The challenge of this method is that path delays should be measured for each chip to configure the tuning buffers properly. Current methods for this delay measurement rely on path-wise frequency stepping. This strategy, however, requires too much time from expensive testers. In this paper, we propose an efficient delay test framework (EffiTest) to solve the post-silicon testing problem by aligning path delays using the already-existing tuning buffers in the circuit. In addition, we only test representative paths and the delays of other paths are estimated by statistical delay prediction. Experimental results demonstrate that the proposed method can reduce the number of frequency stepping iterations by more than 94% with only a slight yield loss. [ABSTRACT FROM AUTHOR]

A new type of steel-reinforced concrete (SRC) rocking sub frame is proposed based on the research of rocking wall. With a 6-story reinforced concrete frame structure as the research object, three kinds of finite element models of frame structure, RC frame rocking wall structure, rocking SRC sub-frame-frame structure were established by finite element software SAP2000, and the seismic performance difference of these three structures was compared by pushover analysis. The results show that the rocking sub-frame can improve the lateral bearing capacity of the frame structure, improve the ductility of the structure and optimize the structure energy dissipation mechanism. [ABSTRACT FROM AUTHOR]