Numerical analysis of nozzle shape effect on fluid motion in LPCVD batch-type furnace

Journal of Mechanical Science and Technology - The importance of equipment technology for semiconductor mass production is growing as well as the exponential increase in demand for semiconductors....     

Flow rate impact on the performance of immobilized nanoFeCu for sewage treatment and its reusability

Ammonia pollution is a global issue, and it endangers human and aquatic life. The role of nanoFeCu in oxidizing ammonia has been identified, but its practicality and performance on the pilot scale are still unclear. This study was conducted to investigate immobilized nanoFeCu's performance in terms of ammonia, nitrate, nitrite, biological oxygen demand (BOD), chemical oxygen demand (COD), and total suspended solid (TSS) by using sewage as feed. The effect of sewage flow rate was studied to determine the optimum operating condition of a pilot-scale reactor. The reusability test was conducted to address sustainability concerns. The nanoFeCu was synthesized, immobilized in polymer clay, and placed into the reactor filled with sewage at a varied flow rate of from 210 to 1200 mL/min. Results showed that a higher sewage flow rate increased the ammonia removal rate within a shorter time but exhausted the immobilized nanoFeCu at a higher rate. Nitrate, nitrite, and TSS have a similar removal trend as ammonia. 800 mL/min was identified as the optimum flow rate with effluent ammonia concentration below 10 ppm in 9 h and maintained for 12 h. A reusability study showed that immobilized nanoFeCu could be reused for at least 10 successive cycles. The stability and performance of immobilized nanoFeCu suggested that it could be an alternative to treat sewage wastewater for real-life applications.     

An Optimization-based SPH Solver for Simulation of Hyperelastic Solids

This paper proposes a novel method for simulating hyperelastic solids with Smoothed Particle Hydrodynamics (SPH). The proposed method extends the coverage of the state-of-the-art elastic SPH solid method to include different types of hyperelastic materials, such as the Neo-Hookean and the St. Venant-Kirchoff models. To this end, we reformulate an implicit integration scheme for SPH elastic solids into an optimization problem and solve the problem using a general-purpose quasi-Newton method. Our experiments show that the Limited-memory BFGS (L-BFGS) algorithm can be employed to efficiently solve our optimization problem in the SPH framework and demonstrate its stable and efficient simulations for complex materials in the SPH framework. Thanks to the nature of our unified representation for both solids and fluids, the SPH formulation simplifies coupling between different materials and handling collisions.     

Stretchable High-Resolution User-Interactive Synesthesia Displays for Visual–Acoustic Encryption

Multifunctional displays, which have various functions in single-device systems without external circuits, are actively investigated as future human–machine interfaces owing to performability of unprecedented functions in compact design. However, their application is limited to visualize the mechanical/electrical signals in light. Herein, stretchable high-resolution multicolor synesthesia display, which can generate synchronized sound and light as input/output sources, is presented by transfer-printing. Transfer-printed emissive composite leads to display with enhanced optical performance and fine sound pressure level. Owing to inherent stretchability of the device, the synesthesia display can stably operate under static and dynamic deformation without distortion in sound relative to the input waveform. User-interactive synesthesia displays are demonstrated for visual−acoustic encryption, which facilitate advanced encryption, as well as multiplex quick response code that bridges multiple domains with a single device. This approach provides new directions for multifunctional displays, with potential applications in reinforced authentication.     

A numerical study on the effect of varying viscosity on the heat transfer inside pipes under low temperature conditions

For a reliable design of a thermal system with oil, which shows drastic change of material properties under low temperature condition, an improved prediction model is necessary because conventional correlations have limited applicability. In this paper, a numerical study on a single and concentric pipes was conducted with i) hydrodynamically fully developed and ii) uniform velocity profiles. Under a low inlet temperature condition, the fully developed velocity profile produced a z-shaped Nusselt number variation with the inverse Graetz number due to the velocity reset and re-developing mechanism. In contrast, the uniform velocity profile showed a large Nusselt number in the entrance region compared to the conventional correlation. Additionally, the simulations were carried out for parallel and counter flow arrangements. Then the Nusselt number correlations were suggested, using a sigmoidal function to reflect the z-shaped pattern. Finally, calculated friction factors were summarized and compared with the conventional correlations.

     

Embedded nanoFeCu for sewage treatment: Laboratory-scale and pilot studies

Bimetallic nanoparticles have been widely studied for wastewater treatment, but the study of nanoFeCu for sewage treatment is minimal. In the previous work, ammonia was removed by nanoFeCu via an oxidation reaction, and nitrogen gas was released. However, the performance and reusability of nanoFeCu in treating industrial wastewater have not been reported elsewhere. This study revealed the performance of nanoFeCu for sewage treatment on both laboratory-scale and pilot-scale for the first time. A varied mass of embedded nanoFeCu (eFeCu4) was exposed to sewage water, and the quality of the effluent was measured in terms of ammonia, biological oxygen demand (BOD), and chemical oxygen demand (COD) removal. Fe²⁺ and Cu²⁺ concentrations were measured to determine the stability of eFeCu4 in nine reuse cycles. Results showed that the laboratory-scale experiment removed 20%–30% ammonia from sewage. A similar removal rate was reported in all nine cycles of reuse, which confirmed the usability and reliability of eFeCu4. In the pilot-scale study, ammonia was removed from ~22.3 to ~4.8 mg/L, while BOD and COD were reduced from ~204 to ~56 mg/L and ~71 to ~39.7 mg/L, respectively. The treated effluent quality complies with the effluent discharge standard of Malaysia, and it is also comparable with the effluent quality at sewage treatment plants in Malaysia and overseas. In conclusion, nanoFeCu could be an alternative method for sewage treatment due to its stability and pollutant removal performance. A sustainability and cost-effectiveness study should be conducted to determine the feasibility of a full-scale application.     

Multiprogramming a distributed-memory multiprocessor

The development of computing systems with large numbers of processors has been motivated primarily by the need to solve large, complex problems more quickly than is possible with uniprocessor systems. Traditionally, multiprocessor systems have been uniprogrammed, i.e., dedicated to the execution of a single set of related processes, since this approach provides the fastest response for an individual program once it begins execution. However, if the goal of a multiprocessor system is to minimize average response time or to maximize throughput, then multiprogramming must be considered. In this paper, a model of a simple multiprocessor system with a two-program workload is reviewed; the model is then applied to an Intel iPSC/2 hypercube multiprocessor with a workload consisting of parallel wavefront algorithms for solving triangular systems of linear equations. Throughputs predicted by the model are compared with throughputs obtained experimentally from an actual system. The results provide validation for the model and indicate that significant performance improvements for multiprocessor systems are possible through multiprogramming.