Synthesis of Nano-Structured Monoclinic W0\u3csub\u3e3\u3c/sub\u3e Particles

The goal of this research is: 1) to develop synthetic methods for generating nanosized particles of monoclinic W03 (m-W03) and 2) to use the high surface area of the nano-sized material in infrared spectroscopic studies of the reactions of gaseous molecules with the particulate surface. Two methods of making nano-structured monoclinic tungsten trioxide (m-W03) particles are investigated. In one method, the sol formation occurs in the presence of a solution containing chelating agents and in a second approach, the sol formation occurs in a water-in oil emulsion. Commercial m-W03 particles are approximately 1 micron in diameter (surface area of about 1.7 m2/g). Particles of this size are not suitable for infrared studies. In contrast, particles produced using the chelating agents have surface areas of about 20m21g whereas a higher value (about 45m2/g) is obtained via the emulsion method. Particles produced with either of these two alternate methods are shown to be suitable for infrared studies. The focus of our synthetic effort centered on altering the conditions used in the condensation step of the reaction. In Chapter 3, we describe our results obtained using chelating agents to slow down the rate of condensation and to impede particle growth. Specifically, acetic acid, oxalic acid dihydrate, and the mixture of the two were added at different concentrations and as a function of pH. Raman, XRD, FTIR, SEM, BET (N2) were used to characterize the oxide product. In chapter 4 we examine an alternative strategy using water-in-oil (W/O) emulsions. The condensation occurs in the aqueous phase inside a surfactant stabilized water droplet. In essence, the droplet is a micro-reactor limiting the size of the final W03 particles. Results obtained using different concentrations of tungstic acid and different molar ratio of water to surfactant (R) are discussed in this thesis. Our experiments show that the emulsion method leads to smaller particles than possible with using chelating agents. In Chapter 5 we demonstrate the usefulness of the nano-sized particles for surface infrared studies. Specifically, we identify the changes that occur in the dehydroxylation/dehydration and Lewis acidity of the surface of monoclinic tungsten oxide (m-W03) powder as a function of evacuation temperature. It is shown that the m-W03 surface at room temperature contains both isolated and hydrogen bonded hydroxyl groups along with layer of adsorbed water and that both the surface hydroxyl groups and adsorbed water layer are eliminated by evacuation at 150°C. Reactions with D20 and pyridine show that the surface hydroxyl groups are accessible, ionic in character and easily displaced. However, the removal of the hydroxyl groups does not lead to exposure of underlying Lewis sites but rather to a reduction in the total number of adsorption sites on the surface. While dramatic changes in surface sites occur between ambient and 150°C, there are few changes with evacuation between 150°C and 400°C

Transport polymerization for materials synthesis.

Ultrathin (10 nm ∼ 1 μm) poly(ethyl 2-cyanoacrylate) (PECA) films were prepared on flat surfaces via vapor deposition without experiencing the liquid phase. System pressure, monomer temperature, as well as surface initiators were studied in the process of controlling the thickness and roughness of polymer films. The growth of poly(ethyl 2-cyanoacrylate) film from patterned initiating surfaces resulted in patterned polymer films. Bulk and surface modifications have been studied in this dissertation to expand the application of poly(ethyl 2-cyanoacrylate) thin films. Polymer/metal composites were prepared using supercritical carbon dioxide. It was found that platinum formed homogeneous particles in poly(ethyl 2-cyanoacrylate) films, when poly(ethyl 2-cyanoacrylate)/poly(para-xylylene) (PPX) multilayer thin films were used as substrate for the platinum deposition, particles formed continuous layer in PECA layer while Transmission electron microscopy (TEM) did not show any platinum particles in PPX layer, which enabled the preparation of alternative conducting-isolating layers. Different functionalities can be introduced to the surface of poly(ethyl 2-cyanoacrylate) films after anhydrides, isocyanates and acyl chlorides reacted with PECA film which was reduced by LiAlH4 and BH3. X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and contact angle measurement indicated that the reaction yield was not high, but for special applications, this method may still be useful. Vapor deposition of ethyl 2-cyanoacrylate was also applied to the nano channels of anodized aluminum membrane (AAM). PECA layers with different thicknesses can be obtained on the inner wall of the nano channels by tuning vapor flow rate, temperature and vapor deposition time. PECA nanotubes were obtained after the removal of the anodized aluminum membrane. PPX/PECA coaxial nanotubes with PPX-outer shell and PECA-inner shell were prepared by using vapor deposition of ethyl 2-cyanoacrylate (ECA) on the AAM-supported PPX nanotubes. Platinum deposition has been applied in the coaxial PPX-PECA nano tubes, platinum particles can be seen by SEM and TEM in the PECA layer or on the PECA inner surface. Gold nano particles were also formed inside of the PECA nanotubes using electroless gold deposition

Understanding ourselves and the environment in which we live

This paper calls for a new methodological paradigm for understanding the adaptive human–nature relationship to achieve a sustainable global environment. It proposes three future research directions: theoretically framing societal processes in natural resources management; establishing a new methodological paradigm for understanding co-evolving human–nature systems; and developing system-scale experimental research

Hyper-Skin: A Hyperspectral Dataset for Reconstructing Facial Skin-Spectra from RGB Images

We introduce Hyper-Skin, a hyperspectral dataset covering wide range of wavelengths from visible (VIS) spectrum (400nm - 700nm) to near-infrared (NIR) spectrum (700nm - 1000nm), uniquely designed to facilitate research on facial skin-spectra reconstruction. By reconstructing skin spectra from RGB images, our dataset enables the study of hyperspectral skin analysis, such as melanin and hemoglobin concentrations, directly on the consumer device. Overcoming limitations of existing datasets, Hyper-Skin consists of diverse facial skin data collected with a pushbroom hyperspectral camera. With 330 hyperspectral cubes from 51 subjects, the dataset covers the facial skin from different angles and facial poses. Each hyperspectral cube has dimensions of 1024$\times$1024$\times$448, resulting in millions of spectra vectors per image. The dataset, carefully curated in adherence to ethical guidelines, includes paired hyperspectral images and synthetic RGB images generated using real camera responses. We demonstrate the efficacy of our dataset by showcasing skin spectra reconstruction using state-of-the-art models on 31 bands of hyperspectral data resampled in the VIS and NIR spectrum. This Hyper-Skin dataset would be a valuable resource to NeurIPS community, encouraging the development of novel algorithms for skin spectral reconstruction while fostering interdisciplinary collaboration in hyperspectral skin analysis related to cosmetology and skin's well-being. Instructions to request the data and the related benchmarking codes are publicly available at: \url{https://github.com/hyperspectral-skin/Hyper-Skin-2023}.Comment: Skin spectral datase

Understanding the Spatial Structure of Urban Commuting Using Mobile Phone Location Data: A Case Study of Shenzhen, China

Understanding commuting patterns has been a classic research topic in the fields of geography, transportation and urban planning, and it is significant for handling the increasingly serious urban traffic congestion and air pollution and their impacts on the quality of life. Traditional studies have used travel survey data to investigate commuting from the aspects of commuting mode, efficiency and influence factors. Due to the limited sample size of these data, it is difficult to examine the large-scale commuting patterns of urban citizens, especially when exploring the spatial structure of commuting. This study attempts to understand the spatial structure characteristics generated by human commutes to work by using massive mobile phone datasets. A three-step workflow was proposed to accomplish this goal, which includes extracting the home and work locations of phone users, detecting the communities from the commuting network, and identifying the commuting convergence and divergence areas for each community. A case study of Shenzhen, China was implemented to determine the commuting structure. We found that there are thirteen communities detected from the commuting network and that some of the communities are in accordance with urban planning; moreover, spatial polycentric polygons exist in each community. These findings can be referenced by urban planners or policy-makers to optimize the spatial layout of the urban functional zones. Document type: Articl

Deca : a garbage collection optimizer for in-memory data processing

In-memory caching of intermediate data and active combining of data in shuffle buffers have been shown to be very effective in minimizing the recomputation and I/O cost in big data processing systems such as Spark and Flink. However, it has also been widely reported that these techniques would create a large amount of long-living data objects in the heap. These generated objects may quickly saturate the garbage collector, especially when handling a large dataset, and hence, limit the scalability of the system. To eliminate this problem, we propose a lifetime-based memory management framework, which, by automatically analyzing the user-defined functions and data types, obtains the expected lifetime of the data objects and then allocates and releases memory space accordingly to minimize the garbage collection overhead. In particular, we present Deca,1 a concrete implementation of our proposal on top of Spark, which transparently decomposes and groups objects with similar lifetimes into byte arrays and releases their space altogether when their lifetimes come to an end. When systems are processing very large data, Deca also provides field-oriented memory pages to ensure high compression efficiency. Extensive experimental studies using both synthetic and real datasets show that, in comparing to Spark, Deca is able to (1) reduce the garbage collection time by up to 99.9%, (2) reduce the memory consumption by up to 46.6% and the storage space by 23.4%, (3) achieve 1.2× to 22.7× speedup in terms of execution time in cases without data spilling and 16× to 41.6× speedup in cases with data spilling, and (4) provide similar performance compared to domain-specific systems

Pathways, volume transport, and seasonal variability of the lower deep limb of the Pacific Meridional Overturning Circulation at the Yap-Mariana Junction

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Wang, J., Wang, F., Lu, Y., Ma, Q., Pratt, L. J., & Zhang, Z. Pathways, volume transport, and seasonal variability of the lower deep limb of the Pacific Meridional Overturning Circulation at the Yap-Mariana Junction. Frontiers in Marine Science, 8, (2021): 672199, https://doi.org/10.3389/fmars.2021.672199.The lower deep branch of the Pacific Meridional Overturning Circulation (L-PMOC) is responsible for the deep-water transport from Antarctic to the North Pacific and is a key ingredient in the regulation of global climate through its influence on the storage and residence time of heat and carbon. At the Pacific Yap-Mariana Junction (YMJ), a major gateway for deep-water flowing into the Western Pacific Ocean, we deployed five moorings from 2018 to 2019 in the Eastern, Southern, and Northern Channels in order to explore the pathways and variability of L-PMOC. We have identified three main patterns for L-PMOC pathways. In Pattern 1, the L-PMOC intrudes into the YMJ from the East Mariana Basin (EMB) through the Eastern Channel and then flows northward into the West Mariana Basin (WMB) through the Northern Channel and southward into the West Caroline Basin (WCB) through the Southern Channel. In Pattern 2, the L-PMOC intrudes into the YMJ from both the WCB and the EMB and then flows into the WMB. In Pattern 3, the L-PMOC comes from the WCB and then flows into the EMB and WMB. The volume transports of L-PMOC through the Eastern, Southern, and Northern Channels all exhibit seasonality. During November–April (May–October), the flow pathway conforms to Pattern 1 (Patterns 2 and 3), and the mean and standard deviation of L-PMOC transports are −4.44 ± 1.26 (−0.30 ± 1.47), −0.96 ± 1.13 (1.75 ± 1.49), and 1.49 ± 1.31 (1.07 ± 1.10) Sv in the Eastern, Southern, and Northern Channels, respectively. Further analysis of numerical ocean modeling results demonstrates that L-PMOC transport at the YMJ is forced by a deep pressure gradient between two adjacent basins, which is mainly determined by the sea surface height (SSH) and water masses in the upper 2,000-m layer. The seasonal variability of L-PMOC transport is attributed to local Ekman pumping and westward-propagating Rossby waves. The L-PMOC transport greater than 3,500 m is closely linked to the wind forcing and the upper ocean processes.This study was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (grant XDA22000000), the National Natural Science Foundation of China (grants 91958204 and 41776022), the Key Research Program of Frontier Sciences, CAS (grant QYZDB-SSW-SYS034), and the International Partnership Program of CAS (grant 133137KYSB20180056). FW thanks the support from the National Natural Science Foundation of China (grants 41730534 and 41421005). QM thanks the support by the National Natural Science Foundation of China (grant 42006003)

Research on Comprehensive Evaluation of Electricity Market Risk Based on Subjective and Objective Weighting

[Introduction] With the emphasis and promotion of the electricity market system construction by the government, the electricity market is constantly growing towards a deeper and more unified direction. In order to promote the electricity market construction, the influence factors of the electricity market risk and its evaluation remain to be studied further. [Method] Based on the consideration of the whole cycle of electricity market trading, this paper took pre-trade risk, during-trade risk, and post-trade riskas the entry points, integrated the existing risks in each stage of electricity market, and established the risk evaluation index system for electricity market. Based on the thought of subjective and objective weighting, analytic hierarchy process (AHP) and entropy weight method were used to assign weights to the index system respectively, and fuzzy comprehensive evaluation (FCE) was adopted to evaluate the comprehensive risk level of the electricity market. [Result] The rationality, comprehensiveness and validity of the proposed model are verified through the analysis of the calculation examples of different electricity markets. [Conclusion] The model eatablished in this paper can conduct a comprehensive risk evaluation for the electricity market, and provide a theoretical reference for the construction of the risk system of the electricity market and its future development direction

Trend analysis of Water Poverty Index for assessment of water stress and water management polices: a case study in the Hexi Corridor, China

The Hexi Corridor, an important part of the Silk Road Economic Belt, is considered the poorest, most water scarce, and most ecologically fragile area in China. Establishing efficient strategies for water management in an integrated manner is utterly important. This paper evaluates the spatio-temporal trends of water stress (2003–2015) in the Shule (SLRB), Heihe (HHRB), and Shiyang (SYRB) River Basins in the Hexi Corridor based on the Water Poverty Index (WPI). For SLRB, the WPI ranged from 55.3 to 66.4, followed by HHRB (40.1–58.2) and SYRB with WPI = 20.0–43.9. Both SYRB and HHRB showed an improvement in the water situation based on increasing trends, whereas SLRB demonstrated a small decrease. The effectiveness of water policy interventions was evident in SYRB and HHRB, standing at odds with SLRB where interventions required adjustment to ameliorate the water stress. For the start and end years, pentagrams for five components (Resource, Access, Capacity, Use, Environment) demonstrated the merits and weaknesses of WPI as a comparative framework for assessing the water situation. This study also reaffirms the importance of WPI, utilized for investigating the efficacy of implemented water policies and benchmarking the future priorities in basins not only in China but also in other locations where water resources management is a key issue