Miniaturization, low cost and high performance of accelerometers have been the topic of extensive research. A kind of convective micromachined accelerometer without proof mass is described in this paper. It consists of a microheater and two temperature sensors which measure the temperature difference between two sides of the microheater caused by the effect of acceleration on free convection. The optimization consideration is conducted before fabrication; some key factors, heater size and power, cavity size, distance between the heater and the sensor and the working medium, are considered. The test for the optimized device shows that the linearity error is smaller than 0.35% under tilt conditions of natural gravity and smaller than 2% under acceleration to 10 g (g = 9.81 m s-2). A sensitivity of 600 µV g-1 is measured for operating power of 87 mW, the response frequency is about 75 Hz and the corresponding noise equivalent acceleration is approximately 1 mg Hz-1/2 at 25 Hz. The dependence of the sensitivity on the heating power is a nearly linear function and the resolution increases with heating power increasing.
During aquifer pumping tests in the field, the attenuation process of the pumping rate is generally monitored, and the aquifer may be slanted, especially in riverbank terraces, piedmont plain and other similar terrains. The combination of these two factors (attenuation process and aquifer slope) has not received enough academic attention, therefore, a two-dimensional groundwater flow model is developed for an exponentially decreasing variable rate pumping well in a sloping aquifer in this study. The new semi-analytical solution (based on a linearized free-surface boundary) is obtained using the Laplace transform and finite Fourier cosine transform. Meanwhile, to depict the linearized boundary precisely with the first-order free surface equation, a numerical model that considers the decline of the water table is also developed. Results show that under the effect of the variable rate, the time-drawdown curve presents a downward trend at intermediate times. Additionally, the error caused by the linearization of the free-surface equation on the analytical model is found to be acceptable except when the sloping angle is larger than π/6. Furthermore, since this study extends the work of Huang et al. (2014), who considered a constant pumping rate, the new solution was found better to interpret real pumping test data reported by Antonio and Pacheco (2002), and the laboratory experiment results. Overall, the new solution proves to be useful for parameter inversion accurately as the average pumping rate tended to underestimate hydraulic parameters when fitting short-term pumping data.
The increasing attention on the applications of advanced robust control to automotive motivates the investigation of engine mount. The state-space frequency domain identification method is used to construct a model for robust control design. Then an H/sub /spl infin// controller is calculated by the linear inequality matrix algorithm for the vibration suppression of engine mount.
A latching acceleration switch with cylindrical contacts is presented in this paper. The cylindrical contacts can make the switch immune to the fabrication imperfection and off sensitive axis shocks, as well as decrease the contact resistance. Moreover, all the contacts and their beams are separated from the proof-mass so as to prevent the contacts from the impact resulting from the rebound or vibration of the proof mass once the switch is latched. The switch was fabricated by low-cost process and tested. The measured latching shock is 4500 G and the response time is less than 0.1 ms. The total on-resistance is less than 3 ohms while the insulation resistance is more than 200 M ohms and the maximum allowable current is up to 130 mA.
In this paper, jarosite residue (JR) blended with concentrated H2SO4 was subjected to a process comprising microwave roasting and water leaching. The effects of H2SO4/JR weight ratio, microwave roasting temperature and time, water leaching conditions on the recovery of Fe, Zn, In, Cu, Cd, Ag and Pb were investigated utilising a series of experiments.Based on energy conservation and environmental protection, optimum conditions for metals recovery from JR were determined as: H2SO4/JR weight ratio = 0.36, microwave roasting temperature, 250°C; roasting time, 30 min; leaching temperature, 50°C; leaching time, 1 h; and liquid–solid ratio, 4:1 (mL/g), thus, the extraction of Fe, Zn, In, Cu, Ag and Cd were 89.4, 80.7, 85.1, 90.7, 61.3 and 48.8% respectively, while the Pb was concentrated in the final residue. Scanning electron microscope-energy dispersive spectrometer (SEM-EDS) patterns were used to characterise and analyse the transformation of valuable metals in the residue after roasting and leaching.
Intercultural communicative competence (ICC) has been accentuated with the wave of globalization. Universities in China have highlighted ICC in language classrooms. Following Byram’s (1997) ICC model (including knowledge, skills, and attitudes), this study focuses on the efficacy of explicit instruction in developing ICC among EFL (English as a Foreign Language) learners in classrooms in China, and to discover how this development is related to the English proficiency. This research, therefore, has two purposes: (1) to use a mix of quantitative and qualitative methods to assess ICC including questionnaires through self and others after explicit instruction. And (2) to investigate the relationship between the development of ICC and English proficiency. The results show that (1) explicit instruction is effective in raising students’ development of ICC, especially the knowledge and skills, and (2) English proficiency is significantly related to better acquisition of ICC. In order to promote learners’ ICC based on the mentioned results, some methods can be adopted: refine the intercultural content, manifest the teaching objectives, improve the involvers’ initiatives and implement the scientific evaluation.
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