Effects of H2 on the number concentration of particulate matter in diesel engines using a low-pressure loop exhaust-gas recirculation system

We investigated the effects of H₂ on the number concentration of particulate matter (PM) emissions from a diesel engine fitted with a low-pressure loop exhaust gas recirculation system. We used a 2.2-L four-cylinder direct-injection diesel engine satisfying EURO V regulations, and converted this engine to include an H₂ feed. The air/fuel (A/F) ratio was varied in the range of 21.9–45.5 and the brake mean effective pressure was varied in the range of 2–6 bars to control the O₂ concentration and in-cylinder temperature, both of which are significant for PM emissions. The number concentration of the emitted PM was measured using a scanning mobility particle sizer. We found that the emitted PM decreased by the addition of H₂ which caused the unburned gas temperature increased. Furthermore, the degree of reduction was larger as the A/F ratio, load, and H₂ energy fraction increased. However, with A/F ratios of less than 21.9, the addition of H₂ increased the number concentration of emitted PM which was attributed to the small O₂ concentration at these A/F ratios.     

Detection of DNA-hybridization using a near-field scanning microwave microscope

A near-field scanning microwave microscope (NSMM) is used to detect sequence-specific hybridization between surface-immobilized and free DNA single strands. Hybridization between target (free) and capture (immobilized) sequences leads to changes in the reflection coefficient (S11) which are measured by the NSMM. These changes are caused by hybridization-induced modification of the dielectric constant profile of the DNA film. NSMM instrumentation does not require labeling of target sequences with fluorophores or other tagging groups. The physical basis of reflection coefficient changes underpinning the NSMM approach is discussed.     

Phase behavior analysis of heavy oil containing asphaltene

A thermodynamic asphaltene precipitation model was developed based on the model of Nghiem et al. using the Peng-Robinson equation of state (PR EOS). This model calculates the amount of asphaltene precipitation based on changes in temperature and pressure. The effects of asphaltene precipitation on rock properties were investigated by observing changes in porosity and permeability. In this model, phase equilibrium was achieved by repeatedly reducing the amount of the asphaltene component, in contrast to the model of Qin et al. using the secant method. The results of this model were compared with experimental data of measured precipitation, based on changes in pressure, and agreed more closely than the model of Qin et al. Our results also confirmed that the maximum precipitation of asphaltene occurred at the bubble-point pressure. Thus, using the model, we verified that the precipitation pattern of asphaltene depended on temperature and pressure, and it is expected that changing patterns in reservoir productivity can be analyzed using asphaltene precipitation in heavy oil-containing asphaltene.     

A study on the optimal design of a cyclone system for vacuum cleaner with the consideration of house dust

Cyclone, a type of particle collector widely used in the field of ambient sampling and industrial particulate control, is the principal type of gas-solids separator that use a centrifugal force. The goal of this study is to transform conventional cyclone into a new type of cyclone that can be used for the household vacuum cleaners. To meet the goal, first, the analysis about local environment and dust is carried out. Second, it must have enough high-efficiency not to reduce suction power due to clogging of exhaust filter unit. Two single cyclones with central-hopper-dust-outlet and side-wall-dust-outlet and a twin cyclone are designed and fabricated to evaluate, and compare, their dust collection efficiencies and pressure drops. The measurements of separation efficiency for dust by using DMT test dust type 08 are carried out. House dust experiment is additionally performed to check the local matters applicability such as tissue papers, fur and hairs. The collection efficiency of the twin cyclone is found to be 3–6% greater than those of two single cyclones with the same body diameter, inlet and inner cylinder diameter. Twin cyclone with a large body diameter, a small inner cylinder diameter, a short inner cylinder, a narrow inlet has high separation efficiency. This result indicates the possibility of achieving higher collection efficiencies with a twin cyclone.     

Building information modelling (BIM) framework for practical implementation

Recent advances in building information modelling (BIM) have disseminated the utilization of multi-dimensional (nD) CAD information in the construction industry. Nevertheless, the overall and practical effectiveness of BIM utilization is difficult to justify at this stage. The purpose of this paper is to propose a BIM framework focusing on the issues of practicability for real-world projects. Even though previous efforts in the BIM framework have properly addressed the BIM variables, comprehensive issues in terms of BIM effectiveness need to be further developed. A thorough literature review of computer-integrated construction (CIC) and BIM was performed first in order to interpret the BIM from a global perspective. A comprehensive BIM framework consisting of three dimensions and six categories was then developed to address the variables for theory and implementation. This framework can provide a basis for evaluating promising areas and identifying driving factors for practical BIM effectiveness.     

Prosocial Activists in SNS: The Impact of Isomorphism and Social Presence on Prosocial Behaviors

The advent of information and communication technology has made people practice prosocial behavior in social networking services (SNSs) more easily. For this reason, the aim of the study was to identify the social and individual factors that induce prosociality in SNS. The concept of isomorphism for categorizing the characteristics of each social networks was adopted. The study also considered the concept of social presence for representing each individual. The experiment manipulated types of isomorphism (Mimetic, Normative, and Coercive) and degrees of social presence in an experimental SNS context. The study also measured individuals’ intention and activity of prosocial behavior. The experiment results indicate that mimetic and normative isomorphic conditions induce higher levels of prosocial intention and activity than coercive isomorphic condition. Also, a higher degree of social presence induces a higher level of prosocial intention. More interesting, the impact of mimetic condition is stronger when the social presence is higher.     

Magnetic properties of hydrogen-included TiZrNiPd quasicrystals

Quasicrystals prepared by rapid quenching of Pd-added TiZrNi ingots were hydrogenated, and effects of hydrogen for magnetic properties were compared with the unhydrogenated ones under magnetic fields from -10000 to 10000 Oe. The magnetization values obtained from vibrating sample magnetometer (VSM) were analyzed with the combination of powder X-ray diffraction (XRD) data. While its contribution is larger than that of Pd, hydrogen decreases the magnetic moments of both Pd-doped and undoped quasicrystals. As increasing the amount of absorbed hydrogen which is represented by H/M (hydrogen to host metal atom ratio) values from 0 to 1.19, the magnetization values of Ti53Zr27Ni20 quasicrystals measured at 10000 Oe significantly decreased from 0.301 to 0.212 emu/g. A careful analysis of XRD data demonstrated that the reduced interactions of magnetic dipole moments between Ni atoms, as the product of the expansion of the quasilattice constants after hydrogenation, are responsible for the decreased magnetization values in hydrogenated TiZrNiPd quasicrystal samples.     

Supply Switching With Ground Collapse: Simultaneous Control of Subthreshold and Gate Leakage Current in Nanometer-Scale CMOS Circuits

Power gating has been widely used to reduce subthreshold leakage. However, the efficiency of power gating degrades very fast with technology scaling, which we demonstrate by experiment. This is due to the gate leakage of circuits specific to power gating, such as storage elements and output interface circuits with a data-retention capability. A new scheme called supply switching with ground collapse is proposed to control both gate and subthreshold leakage in nanometer-scale CMOS circuits. Compared to power gating, the leakage is cut by a factor of 6.3 with 65-nm and 8.6 with 45-nm technology. Various issues in implementing the proposed scheme using standard-cell elements are addressed, from register transfer level to layout. These include the choice of standby supply voltage with circuits that support it, a power network architecture for designs based on standard-cell elements, a current switch design methodology, several circuit elements specific to the proposed scheme, and the design flow that encompasses all the components. The proposed design flow is demonstrated on a commercial design with 90-nm technology, and the leakage saving by a factor of 32 is observed with 3% and 6% of increase in area and wirelength, respectively.