Two Case Histories of Alkali Liquid Method to Reinforce Collapsible Loess Deposit

Presented in this paper is the summary of two case histories using alkali liquid method to reinforce collapsible Loess ground. One is the ground treatment of administration building which was not in a position of normal service because of the unequal settlement of the ground caused by collapsibility; the other is the ground improvement of the office building of a hospital before construction. The test to examine reinforcing effects is held one month after ground stabilization. It is learned from the test results that the soil compressibility characteristics within the treated aera has been changed from high grade to medium grade or tow grade, and the collapsibility of loess within the treated area has been eliminated. The method of alkali liquid to improve ground has many advantages, namely, simple in construction, with obvious effects, and no vibration or contamination to be caused

Twice Dynamic Consolidation — An Unusual Application in Treating Liquefiable Saturated Sandy Loam Deposits

More innovative methods of ground treatment have replaced traditional methods. Dynamic consolidation, for example, has been applied widespreadly in China. Presented in this paper is a case history of adopting the twice dynamic consolidation method to improve liquefiable saturated loesslike sandy loam deposit, since the site for the Aluminum Material Company which is located at the suburb of Talyuan, China, Is geotechnically adverse. In this project the effective depth of improvement increased significantly. Judged from the ln-situ investigation and laboratory triaxial shear test, the liquefaction potential was eliminated as predicted

Nonlinear System Modeling, Optimal Cam Design, and Advanced System Control for an Electromechanical Engine Valve Drive

A cam-based shear force-actuated electromechanical valve drive system offering variable valve timing in internal combustion engines was previously proposed and demonstrated. To transform this concept into a competitive commercial product, several major challenges need to addressed, including the reduction of power consumption, transition time, and size. As shown in this paper, by using nonlinear system modeling, optimizing cam design, and exploring different control strategies, the power consumption has been reduced from 140 to 49 W (65%), the transition time has been decreased from 3.3 to 2.7 ms (18%), and the actuator torque requirement has been cut from 1.33 to 0.30 N·m (77%).Sheila and Emanuel Landsman Foundatio

Advanced modeling ,control, and design of an electromechanical engine value drive system with a limited-angle actuator

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 241-242).This thesis addresses a specific variable valve actuation (VVA) system ---- an electromechanical valvetrain ---- in order to provide variable valve timing (VVT) in internal combustion (IC) engines. This electromechanical valve drive (EMV) system was proposed by Dr. Woo Sok Chang and his colleagues in the Laboratory for Electromagnetic and Electronic Systems (LEES), who also validated the feasibility of the design to provide VVT. The goal of this thesis is to bring the MIT EMV system to a more practical level by achieving a smaller package (to fit in the limited space over the engine head), a faster transition time (to accommodate faster engine speed), and a lower power consumption, while still offering satisfactory valve transitions with timing control. This thesis reports four major achievements. First, a more accurate system model, including dynamics, loss flow and distributions, and nonlinear friction, has been established for better guidance in system control and design via numerical simulations. Second, different control strategies and cam designs have been explored in order to determine the most appropriate control strategy and cam design to achieve a lower torque requirement, reduced power consumption and a faster transition time. Third, a limited-angle actuator was custom designed and built for the valve actuation application in order to reduce the actuator size while maintaining the necessary torque and power output. Fourth, with the limited-angle actuator in place, the EMV system was evaluated experimentally for intake valve actuation and numerically for exhaust valve actuation with gas force disturbance taken into consideration. Based on this system evaluation, we are able to project the system's applicability to a real 4-cylinder 16-valve engine with independent valve control for each intake and exhaust valve.(cont.) At the end of the thesis, the power consumption has been reduced from 140 W to 50 W (about 64%), the transition time has been reduced from 3.3 ms to 2.7 ms, and the final actuator volume has been reduced to 1/7 of that of the original motor. These significant improvements enabled the projection of independent valve actuation for a 4-cylinder 16-valve IC engine with reasonable power consumption and high engine speed.by Yihui Qiu.Ph.D

A novel pollution pattern: Highly chlorinated biphenyls retained in Black-crowned night heron (Nycticorax nycticorax) and Whiskered tern (Chlidonias hybrida) from the Yangtze River Delta

AbstractContamination of organochlorine pesticides (OCPs), polychlorinated diphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and their methylated counterparts (MeO-PBDEs) were determined in Black-crowned night heron (Nycticorax nycticorax) and Whiskered tern (Chlidonias hybrida) from two drinking water sources, e.g. Tianmu lake and East Tai lake in Yangtze River Delta, China. A novel PCBs contamination pattern was detected, including 11% and 6.9% highly chlorinated biphenyls (PCBs with eight to ten chlorines) in relation to total PCB concentrations in the Black-crowned night heron and Whiskered tern eggs, respectively. The predominating OCPs detected in the present study were 4,4′-DDE, with concentration range 280–650 ng g−1 lw in Black-crowned night heron and 240–480 ng g−1 lw in Whiskered tern, followed by β-HCH and Mirex. 6-MeO-BDE-90 and 6-MeO-BDE-99 are the two predominant congeners of MeO-PBDEs whereas 6-OH-BDE-47 contributes mostly to the OH-PBDEs in both species. Contamination level was considered as median or low level compared global data

Preparation of Nanofibers with Renewable Polymers and Their Application in Wound Dressing

Renewable polymers have attracted considerable attentions in the last two decades, predominantly due to their environmentally friendly properties, renewability, good biocompatibility, biodegradability, bioactivity, and modifiability. The nanofibers prepared from the renewable polymers can combine the excellent properties of the renewable polymer and nanofiber, such as high specific surface area, high porosity, excellent performances in cell adhesion, migration, proliferation, differentiation, and the analogous physical properties of extracellular matrix. They have been widely used in the fields of wound dressing to promote the wound healing, hemostasis, skin regeneration, and treatment of diabetic ulcers. In the present review, the different methods to prepare the nanofibers from the renewable polymers were introduced. Then the recent progress on preparation and properties of the nanofibers from different renewable polymers or their composites were reviewed; the application of them in the fields of wound dressing was emphasized

Accelerated Nuclear Magnetic Resonance Spectroscopy with Deep Learning.

Nuclear magnetic resonance (NMR) spectroscopy serves as an indispensable tool in chemistry and biology but often suffers from long experimental time. We present a proof-of-concept of application of deep learning and neural network for high-quality, reliable, and very fast NMR spectra reconstruction from limited experimental data. We show that the neural network training can be achieved using solely synthetic NMR signal, which lifts the prohibiting demand for large volume of realistic training data usually required in the deep learning approach

An invasive species erodes the performance of coastal wetland protected areas

The world has increasingly relied on protected areas (PAs) to rescue highly valued ecosystems from human activities, but whether PAs will fare well with bioinvasions remains unknown. By analyzing three decades of seven of the largest coastal PAs in China, including World Natural Heritage and/or Wetlands of International Importance sites, we show that, although PAs are achieving success in rescuing iconic wetlands and critical shorebird habitats from once widespread reclamation, this success is counteracted by escalating plant invasions. Plant invasions were not only more extensive in PAs than non-PA controls but also undermined PA performance by, without human intervention, irreversibly replacing expansive native wetlands (primarily mudflats) and precluding successional formation of new native marshes. Exotic species are invading PAs globally. This study across large spatiotemporal scales highlights that the consequences of bioinvasions for humanity’s major conservation tool may be more profound, far reaching, and critical for management than currently recognized