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Hydraulic fineblanking press is a kind of high-end hydraulic metal forming devices and widely applied in automotive and appliance industry. However, it suffers from the defeat of high energy consumption low energy efficiency. To solve the problem, this study proposed a power-matching strategy by using a novel controllable accumulator which can control the precharge pressure, output flow with high precision. Firstly, the energy characteristics and working performance requirements of the large-sized fineblanking press in a working cycle were investigated. Then, the energy consumption mathematic model coupling with the controllable accumulator was built for designing the key parameters of the accumulators. Based on the load characteristic and the energy model, a controlling strategy of the controllable accumulator was proposed to reduce the imbalance degree of the supplied and demanded power and improve working performance by designing working route of the controllable accumulator. Finally, a detailed hydraulic schematic was designed and applied on the 1000 ton hydraulic fineblanking press, which was validated with simulation model. The results show that compared to the traditional system, the energy efficiency of the novel system is improved by 20.35% with lowering the input energy by 169.4 kJ. Besides, the vibration magnitude of the slide block is decreased a lot and the working production efficiency is improved by 10% compared to the traditional system.

The influences of carbon nanotubes (CNTs) additions on the flash ignition characteristics of Iron (Fe) and aluminum (Al) nanoparticles (NPs) were presented. CNTs can be used as the additive to these metal nanoparticles for improving the flash ignition and burning processes. Different mass fractions of CNTs additions were considered. The mixture of Al and CNTs could combust in air with obvious giant flame, whereas the mixture of Fe and CNTs combusted under a relative stable condition with slight red light. The temperature distributions were measured using non-contact optical method and showed that Al NPs mixed with CNTs were burning at a higher temperature level than Fe NPs. Although different mass fractions of CNTs cannot significantly change the overall flash ignition phenomenon, CNTs additions influenced the minimum ignition energy (MIE) of mixtures. The appropriate content of CNTs addition can decrease the Fe NPs MIE significantly. However, the Al NPs MIE decreased all along with the increase of CNTs content. The micro- and nano- structures of Fe and Al NPs with CNTs additions before and after ignitions were examined by scanning electron microscope and high-resolution transmission electron microscopy. It was found that the special thermal conductive characteristics of CNTs and the cross-connected features for metal particles with CNTs caused the enhancement of flash ignition.

In the present study, Fe nanoparticles (NPs) can ignite when exposed to a conventional camera flash. The ignition process of Fe NPs was composed of the initial ignition stage with the maximum temperature level of 2000 K and the burning stage with temperature level of 800 K. The microstructure characterization indicated Fe NPs were oxidized to Fe2O3 via the exposure-melt mechanism. It was found that more particle numbers per unit area can lead to lower minimum ignition energy which may be caused by the enhancement light energy absorption. The light energy absorbed from the flash was influenced by wavelengths but the conversion of Fe was only related to the packing mass.

To improve the useful energy efficiency of a hydraulic fine-blanking press (HFBP), a hydraulic system using a combined valve-pump combined with multiple accumulators and comprising a valve-controlled circuit and pump-controlled circuit, was presented based on the working-process load characteristics. By adopting multiple accumulators, the slide block mechanical energy was recycled and the system dynamic response speed was improved. The system operation principle was first presented, and the system parameters were calculated based on the energy conservation law. Then, a simulation model was established to analyze the system energy dissipation and distribution. Finally, the proposed system was validated on a 1000-ton HFBP. The results demonstrate that, in comparison with the conventional system, the novel system performs well, while simultaneously achieving a high working speed, high precision and large tonnage. Moreover, the total dissipation energy of this novel system was decreased by approximately 100 kJ in a working cycle, while the energy utilization efficiency was increased by an average of 20% under different load conditions. This novel system can be generalized to any hydraulic press to improve energy efficiency and especially hydraulic presses having a large tonnage.

Microcellular injection molding (MIM) combined with in-mold decoration (IMD) method can produce foamed parts with improved surface appearance by changing the heat transfer in the MIM mold. The temperature field has a significant effect on the forming defects and crystallization of the foamed parts. Based on finite volume method, a multiphase flow-solid coupled heat transfer model was established to calculate the temperature field in IMD/MIM process, and the implicit domain coupling algorithm (IDCA) was used to calculate the temperature field by taking the coupled heat transfer between the mold and the polymer melt into account. Compared with the experimental results, it is found that the established model can accurately predict the temperature field. The thermal response in IMD/MIM process was further analyzed. The effect of film on the forming defects of parts molded by IMD/MIM process was discovered by combining the simulation results with the experimental surface topography and warpage results, and the effect of film on the crystallization of parts molded by IMD/MIM process was also revealed.

The weighted mean tropospheric temperature is a critical parameter in the conversion of wet zenith delay to precipitable water vapor in GPS Meteorology. This parameter can not be calculated from the radiosonde data in real time through the conventional methods. In this study, we first discuss the admissible error of weighted mean temperature to enable the accuracy of the conversion better than 1 mm, then summarize the performance of some of the existing methods. An empirical formula is established that satisfies the real-time requirement in GPS meteorology using Sequential Regression Analysis method. It is shown that this real-time formula as compared with other empirical methods is more accurate for local applications.

Dynamic characteristics of large structures, such as tall buildings, longspan suspension, cable-stayed bridges and tall chimneys, are key to assess their drift and stress conditions. The dynamic characteristics of large structures are difficult to measure directly under the condition of earthquakes or strong winds using traditional techniques such as laser collimator, total station and accelerometers. Therefore there is a great need for developing new method or technique for this purpose. Recent advances in Global Positioning System (GPS) technology provide a great opportunity to monitor long-period changes of structures reliably. GPS receivers capable to gauge the motion at the centimeter or sub-centimeter level with sampling frequency 10Hz or even 20 Hz are now available from several manufacturers. To the authors’ knowledge, the capability of identifying dynamic characteristics from GPS observations has not been widely verified. For the feasibility study on using kinematic GPS technology to identify the dynamic characteristics of tall buildings, some experiments were conducted in a simulative environment. This paper discusses in detail the experiment device, and the ways through them GPS data are recorded, processed and analyzed. With post-processing version of NovAtel’s Softsurv software and auto-regressive (AR) spectral analysis method, relative displacements and corresponding vibrating frequencies have been derived from GPS observations. The results indicate that the dynamic characteristics can be identified accurately by kinematic GPS technology.

Spatial and temporal resolution of water vapor content is useful in improving the accuracy of short-term weather prediction. Dense and continuously tracking regional GPS arrays will play an important role in remote sensing atmospheric water vapor content. In this study, a piecewise linear solution method was proposed to estimate the precipitable water vapor (PWV) content from ground-based GPS observations in Hong Kong. To evaluate the solution accuracy of the water vapor content sensed by GPS, the upper air sounding data (radiosonde) that are collected locally was used to calculate the precipitable water vapor during the same period. One-month results of PWV from both ground-based GPS sensing technique and radiosonde method are in agreement within 1–2 mm. This encouraging result will motivate the GPS meteorology application based on the establishment of a dense GPS array in Hong Kong.