Type synthesis of spatial mechanisms on the basis of spatial single loop structural groupsTypensynthese räumlicher mechanismen auf der grundlage räumlicher einfach geschlossener strukturgruppen

This paper describes the basis for a new method of type synthesis of spatial mechanisms with the use of single-loop structural groups having zero degrees of freedom. Applying the binary system, the value 0 is used for R (revolute) and 1 is used for P (prismatic) pairs. The five-link spatial groups are described by codes both in the binary and decimal systems. All other groups are reduced to the basis of five-link spatial groups. In these cases two-degree-of-freedom and three-degree-of-freedom kinematic pairs are transformed to one-degree-of-freedom pairs, and these transformations are also described by codes in the binary and decimal systems. This method of coding can be programmed for digital computation and applied towards the automatic type synthesis in the design of spatial mechanisms. The system is equally clear for alphanumeric or for graphical display. To the designer it defines the diagram of the mechanism, pointing out the frame, the mobile links, the types of the kinematic pairs and their mutual disposition in the mechanism configuration.     

Intrinsically patterned electrical systems: physical requirements and experimental demonstration

Microsystem Technologies - This paper introduces a method of replicating electrical circuits through a series of specific requirements as part of a design methodology referred to as Intrinsically...     

Analysis of defects on BN nano-structures using high-resolution electron microscopy and density-functional calculations

Cubic boron nitride (c-BN) nucleation takes place on hexagonal boron nitride (h-BN) layers growing perpendicular to the substrate surface during thin film synthesis. Studies focused on the nucleation of the cubic phase suggest the possibility that transient phases and/or defects on these h-BN structures have a role in sp3-bonded cubic phase nucleation. In this study, we have investigated the nature, energetics, and structure of several possible defects on BN basal planes, including point defects, 4-, and 5-fold BN rings, that may possibly match the experimentally observed transient phase fine structure. TEM image observations are used to build approximate atomic models for the proposed structures, and DFT calculations are used to relax these structures while minimizing their respective total energies. These optimized atomic geometries are then used to simulate TEM images, which are compared to the experimentally observed structures. Data from DFT calculations and analysis of simulated images from the proposed atomic structures suggest that 4-fold BN rings are more likely to exist on the transient phase possibly leading to c-BN nucleation.     

MCMR: Maximum coverage and minimum redundant text summarization model

In paper, we propose an unsupervised text summarization model which generates a summary by extracting salient sentences in given document(s). In particular, we model text summarization as an integer linear programming problem. One of the advantages of this model is that it can directly discover key sentences in the given document(s) and cover the main content of the original document(s). This model also guarantees that in the summary can not be multiple sentences that convey the same information. The proposed model is quite general and can also be used for single- and multi-document summarization. We implemented our model on multi-document summarization task. Experimental results on DUC2005 and DUC2007 datasets showed that our proposed approach outperforms the baseline systems.     

Solid solution limit of Fe2O3 in mullite crystals,produced from kaolin by solid state reactions

Porcelain, wall/floor tiles, and roofing tiles are classified as traditional ceramics and are produced from natural raw materials such as clay, quartz, and feldspar. The raw materials are selected by the oxide content which provides the desired properties of the final product. However, impurities such as Fe₂O₃ and TiO₂ may have a significant influence on both physical/mechanical properties and aesthetic appearance. Fe₂O₃, which is of particular importance, causes black maculation formation in tablewares, in which whiteness is essential. The only way to overcome the black maculation is to corrupt the Fe₂O₃ crystal structure and to employ Fe^2+/3+ cation, making a solid solution with a host crystal (i.e. mullite-3Al₂O₃·2SiO₂). The aim of this study is to identify the solubility limit of Fe₂O₃ in mullite crystals. With the scope of the study, an illite/kaolinite was utilized by adding an increasing amount of Fe₂O₃ (e.g. 1–2–4–6–8–10?wt%) into the recipes fired at 1300?°C for 3?h after homogenization. According to the mullite phase content, it is concluded that ~ 5?wt% of Fe₂O₃ could be dissolved in mullite crystal structure on the basis of the Rietveld refinement of the XRD patterns.     

A biophysically based and objective satellite seasonality observation method for applications over the Arctic

Despite wide applications of remote-sensing data with high temporal resolution for monitoring phenology, two persistent problems have prevented the realization of their full potential. The first is the subjectivity in defining thresholds for a phenological event (e.g. the start or end of growing season ? SOS or EOS). The second is the use of various arbitrarily selected filtering and smoothing algorithms for constructing vegetation index seasonal profiles in order to reduce the noise caused by residue cloud contamination and aerosol variations. In this study, we addressed both problems by developing a biophysically based and objective satellite seasonality observation method (BLOSSOM) for application over Canada’s Arctic. Application of the BLOSSOM method to three northern Canadian national parks (Ivvavik, Wapusk, and Sirmilik) proved that the method is operational. Using the uncertainties in the vegetation index and its threshold, we estimated the overall mean uncertainties as being ?5.3 to 3.4 days, ?4.2 to 5.2 days, and ?6.2 to 8.4 days, respectively, for SOS, EOS, and growing season length (GSL). Further independent tests against SOS, determined using records of snow cover at nearby climate stations (as ‘truth’), indicate that the mean absolute error is less than 3.6 ± 0.2 days.     

Tribological behaviour of SiC?TiC?TiB2 composites under unlubricated sliding conditions

The friction and wear behaviour of eight different SiC TiC TiB₂ composite materials, with a practically constant SiC:TiC ratio of 1 and an increasing amount of TiB₂, was determined comparatively in oscillating sliding tests at room temperature under unlubricated conditions. The influence of the relative humidity (RH) of the surrounding air was investigated in tests in dry, normal, and moist air. All tests were performed against SiC balls and Al₂O₃ balls as counterbodies. The friction was affected by RH but barely at all by the composition of the composites. The wear resistance of the composites was found to be improved considerably by addition of TiB₂ in the range 20–60%. The highest wear resistance of the system was found when Al₂O₃ was used as the counterbody material.     

CMUTS with dual-electrode structure for improved transmit and receive performance

In this paper, we introduce capacitive micro-machined ultrasonic transducers (CMUTs) with electrically isolated multiple electrodes embedded in the same silicon nitride CMUT membrane. Some of the advantages of this structure are demonstrated using a dual-electrode CMUT with separate transmit and receive electrodes as an example. By locating the transmit electrodes near the edges of a rectangular CMUT membrane, the stable displacement range, hence the maximum pressure amplitude during transmit mode is increased without collapsing the membrane when operated within static collapse voltage range. In the receive mode, the center receive electrode is brought closer to the substrate by biasing the side electrodes, and a higher electromechanical transformer ratio is obtained at low direct current (DC) bias. Therefore, dual-electrode CMUT has an effectively larger gap as compared to conventional CMUT during transmit, and it has an effectively smaller gap during receive. Demonstrative experiments are performed on dual-electrode CMUTs with rectangular membranes with different side and center electrode sizes for transmit and receive measurements. By using the two 4-microm wide side electrodes and an 8-microm wide center electrode on a 20-microm wide membrane, a 6.8 dB increase in maximum output pressure is obtained with side electrode excitation as compared to conventional center electrode. Similarly, the receive performance improvement was demonstrated while reducing the DC bias requirements. Simple finite-element and equivalent circuit-based models were developed to successfully model the behavior of dual-electrode CMUTs. Simulations show that, with simple modifications, more than 10 dB overall sensitivity improvement is feasible with dual-electrode CMUTs with rectangular membranes.     

Forced convection heat transfer and pressure drop for a horizontal cylinder with vertically attached imperforate and perforated circular fins

In this study, the effect of holes placed on perforated finned heat exchangers on convective heat transfer experimentally investigated. Six millimeter-diameter holes were opened on each circular fin on a heating tube in order to increase convective heat transfer. These holes were placed on the circular fins in such a way as to follow each other at the same chosen angle. The holes created turbulence in a region near the heating tube surface on the bottom of the fin. Some experiments were then performed to analyze the effect of this turbulence on heat transfer and pressure drop. These experiments were carried out at six different angular locations in order to determine the best angular location. In addition, a perforated finned heater was compared with an imperforate finned heater to observe the differences. In the cases of the Re above the critical value, Nusselt numbers for the perforated finned positions are 12% higher than the Nusselt numbers for the imperforate state. Moreover, a correlation has been obtained between the Re and Nu in the Re number above the critical value and the Re below the critical value. Meanwhile, correlations regarding pressure drops in the flow areas have been obtained.     

Magnetization of magnetite nanoparticles mediums with weak magnetic dipole-dipole interaction

Magnetization expression of weak interacting (mH/kT = 1-1.5) magnetite nanoparticles mediums was determined. Experimental and calculated magnetization curves, initial magnetic susceptibility of magnetite nanoparticle mediums were compared. It is showed are agree. Additional term of the magnetization is sufficient at weak and middle magnetic fields and at large magnetic fields it leads to zero. The maximum value of additional term is determined as mH/kT = 1.566 and it is linear function of magnetic moments and parabolic function of concentration of magnetite.