An Instrument for In Situ Measuring the Volume Scattering Function of Water: Design, Calibration and Primary Experiments

The optical volume scattering function (VSF) of seawater is a fundamental property used in the calculation of radiative transfer for applications in the study of the upper-ocean heat balance, the photosynthetic productivity of the ocean, and the chemical transformation of photoreactive compounds. A new instrument to simultaneously measure the VSF in seven directions between 20° to 160°, the attenuation coefficient, and the depth of water is presented. The instrument is self-contained and can be automatically controlled by the depth under water. The self-contained data can be easily downloaded by an ultra-short-wave communication system. A calibration test was performed in the laboratory based on precise estimation of the scattering volume and optical radiometric calibration of the detectors. The measurement error of the VSF measurement instrument has been estimated in the laboratory based on the Mie theory, and the average error is less than 12%. The instrument was used to measure and analyze the variation characteristics of the VSF with angle, depth and water quality in Daya Bay for the first time. From these in situ data, we have found that the phase functions proposed by Fournier-Forand, measured by Petzold in San Diego Harbor and Sokolov in Black Sea do not fit with our measurements in Daya. These discrepancies could manly due to high proportion of suspended calcium carbonate mineral-like particles with high refractive index in Daya Bay

STEADY-STATE THERMAL-HYDRAULIC ANALYSIS OF A PLATE TYPE REACTOR

ABSTRACT In the plate type fuel reactor, all the fuel elements are arranged in parallel in the subassembly and set in the core, which create many isolated parallel rectangular channels. The arrangements of the fuel elements may have significant impact on the thermal-hydraulics of the core. In order to fully understand the geometry impact on the steady-state thermalhydraulic characteristics, based on the mass, momentum and energy conservation equations, a multi-channel code was developed to estimate the steady-state thermal-hydraulic characteristics. Two different types of fuel elements arrangements in the subassembly were proposed and studied, one was uniform distribution with the same gap sizes between each fuel elements, and the other was nonuniform distribution with different clearances among boundary fuel elements. The mass flux distribution, the temperature field and the DNBR were obtained by the developed code. It showed that the mass flux distribution was affected by the flow area of the channel and the given power distribution. The flow area of the channel has bigger influence than the second. In addition, the results of the two different types of fuel elements arrangements were compared, and it could be found that the asymmetrical cooling of the fuel elements occurred when fuel elements were nonuniformly arranged, which leaded to the decrease of the maximum temperature in the asymmetrically cooled fuel elements and the increase of the maximum temperature in the core. Furthermore, the DNBR calculated by the Sudo model indicated that the safety margin of the reactor under the present conditions is sufficient. All the obtained results served some valuable information for the design of the new type research reactor

Reservoir-cap combination optimization and potential evaluation of CO2 geological storage in saline aquifer, in Wenxinan sag of Beibu Gulf Basin

CO2 geological storage is a guaranteed technology for achieving carbon neutrality. The offshore deposit basin is far away from the human activity area, and the implementation of a CO2 geological storage is more advantageous than the land sedimentary basin. To find out the CO2 storage potential in the Weixinan sag of the Beibu Gulf Basin, based on the 8 indicators such as caprock burial depth, the maximum thickness of single layer mudstone, mud-soil ratio, fault density and reservoir porosity, formation thickness, sand-soil ratio, permeability, etc., it has established a reservoir evaluation system for the secondary structure unit of the basin. Combined with the core physical property data of lays and 3D geological models, the reservoir and caprock of the Weixinan sag are optimized, and the effective storage potential is evaluated with the US-DOE method. The results show that within 800−3000 meters below the sea floor, in the Weixinan sag, there are two sets of reservoir-cap combinations suitable for CO2 storage. Combination 1: in Neogene, the neritic mudstone of the first member of the Jiaowei Formation is the cap rock, and the neritic sandstone of the second member of the Jiaowei Formation and the Xiayang Formation is the reservoir, and the effective storage capacity is 0.749 billion tons. Combination 2: in the Paleogene, the deep lake mudstone in the second member of the Weizhou Formation is the cap rock, and the sandstone in the third member of the Weizhou Formation is the reservoir, and the effective storage capacity is 0.374 billion tons. In the Weixinan sag, two sets of reservoir-cap assemblages suitable for CO2 storage in the saline aquifers are selected, with an effective storage capacity of 1.123 billion tons. According to the evaluation of the annual CO2 emission of 70 million tons in the west of Guangdong Province, it can meet the CO2 emission reduction needs of the region for more than 16 years. Offshore geological storage is a potential path for the green and sustainable development of coastal heavy chemical clustering areas and to achieve the goal of carbon neutrality

Efficacy of modified thoraco-laparoscopic Ivor-Lewis versus traditional thoraco-laparoscopic Ivor-Lewis for esophageal cancer: Propensity score-matched analysis

ObjectiveTo compare the clinical results of the modified Ivor-Lewis procedure, which preserves the azygous vein, thoracic duct and surrounding tissues, with the traditional Ivor-Lewis procedure, which removes these tissues, for treating esophageal squamous cell carcinoma, and evaluating whether the azygous vein, thoracic duct and surrounding tissues are required to be removed for the surgery of esophageal cancer.MethodsTo retrospectively analyze the clinical data of patients suffering from esophageal cancer treated by thoracic-laparoscopic Ivor-Lewis procedure admitted to the Department of Thoracic Surgery of Gansu Provincial People’s Hospital from September 2017 to September 2019. According to the surgical method, they were divided into the modified thoracolaparoscopic Ivor-Lewis (modified group) and the traditional thoracolaparoscopic Ivor-Lewis (traditional group). Propensity score matching analysis (PSM) was applied to reduce the selection bias of confounding factors.ResultsA total of 245 patients who suffered from esophageal cancer and underwent thoracic-laparoscopic Ivor-Lewis were enrolled in the study. There were 124 cases in the modified group and 121 cases in the traditional group. The discrepancies in the age and T-stage among patients in the traditional and modified groups were statistically significant. After PSM, the above-mentioned factors became statistically insignificant. There were 86 patients in each group after PSM. Compared with the traditional group, the modified group has shorter operative time (p=0.007), less intraoperative bleeding (p=0.003) and less postoperative 3 days chest drainage(p=0.001), with a statistically significant difference. No significant difference in local recurrence (p=0.721) and distant metastasis (p=0.742) after surgery were found in the two groups, and the difference was not statistically significant. There was also no statistically significant difference in the 3-year postoperative survival rate (44.2% vs. 41.9%, p=0.605) between the modified and traditional groups.ConclusionThe modified Ivor-Lewis procedure, which preserves the azygous vein, thoracic duct, and surrounding tissue, reduces surgical trauma in esophageal cancer, has not increased postoperative recurrent metastases, while achieved the same long-term outcomes as expanded surgery

Diffusion-free Grotthuss topochemistry for high-rate and long-life proton batteries

The design of Faradaic battery electrodes that exhibit high rate capability and long cycle life equivalent to those of the electrodes of electrical double-layer capacitors is a big challenge. Here we report a strategy to fill this performance gap using the concept of Grotthuss proton conduction, in which proton transfer takes place by means of concerted cleavage and formation of O-H bonds in a hydrogen-bonding network. We show that in a hydrated Prussian blue analogue (Turnbull's blue) the abundant lattice water molecules with a contiguous hydrogen-bonding network facilitate Grotthuss proton conduction during redox reactions. When using it as a battery electrode, we find high-rate behaviours at 4,000 C (380 Ag-1, 508 mA cm(-2)), and a long cycling life of 0.73 million cycles. These results for diffusion-free Grotthuss topochemistry of protons, in contrast to orthodox battery electrochemistry, which requires ion diffusion inside electrodes, indicate a potential direction to revolutionize electrochemical energy storage for high-power applications

Essays on trade and export development

The dynamics between industrial development and export activities have been the interest of research for the past two decades, especially those related to services activities and global value chain activities. This thesis contributes to the literature by examining the relationships between industrial upgrading, the similarity of countries’ exports, and the economic development of countries. The thesis also explores the factors that promote export upgrading and policy barriers in services trade across different economies. The thesis is organized as follows. Chapter 1 provides the motivation for the thesis. Chapter 2 highlights the literature on export activities (export similarity index and export quality index) foreign direct investment (FDI), and services activities in global economic development. Chapter 3 investigates the links between export similarity and bilateral FDI of Japan and host countries, exploring in particular how multinational activities (FDI) could increase the export activities of domestic countries. The empirical analysis is conducted using a panel data of 70 countries based on SITC (Standard International Trade Classification) 4- and 5-digit products. The results suggest that: (1) outward FDI from Japan increases export similarity between host and source countries, however, inward FDI to Japan shows no evidence of promoting similarity; (2) bilateral FDI positively promotes similarity in the manufactured exports, but to a lesser extent in primary sector exports; and (3) geographic distances and differences in per capita income have significant negative effects on export similarity. In Chapter 4, the empirical framework is developed to study the impact of policy restrictions on services trade across countries. Recent studies highlight that services are essential for manufacturing productivity improvement and economic development. This chapter examines the relationship between policy restrictions (measured by the services trade restrictiveness index (STRI)) and services trade across countries using data from UN Comtrade. A log-linear gravity model is developed to explain variations in bilateral services-trade volumes. The main results show that: (1) a 1% percent increase in the overall STRI leads to a 0.3% decrease in bilateral services trade and around 0.04% decrease in services export; and (2) both goods-trade networks and merchandise exports similarity have statistically significant and positive influences on services trade. In Chapter 5, the determinants of variations in export quality across countries are investigated. The study empirically examines the dynamic pattern of export upgrading and its main influencers based on a panel framework. The results imply that service imports, FDI inflows and the level of per capita income have positive effects on export quality growth. The last chapter, Chapter 6, provides the policy discussion and conclusion of the thesis, as well as discussing how the study could be extended as part of further research in this area.Thesis (Ph.D.) -- University of Adelaide, School of Economics, 201

Groundwater Contamination Source Recognition Based on a Two-Stage Inversion Framework with a Deep Learning Surrogate

Groundwater contamination source recognition is an important prerequisite for subsequent remediation efforts. To overcome the limitations of single inversion methods, this study proposed a two-stage inversion framework by integrating two primary inversion approaches—simulation-optimization and simulation-data assimilation—thereby enhancing inversion accuracy. In the first stage, the ensemble smoother with multiple data assimilation method (a type of simulation-data assimilation) conducted a global broad search to provide better initial values and ranges for the second stage. In the subsequent stage, a collective decision optimization algorithm (a type of simulation-optimization) was used for a refined deep search, further enhancing the final inversion accuracy. Additionally, a deep learning method, the multilayer perceptron, was utilized to establish a surrogate of the simulation model, reducing computational costs. These theories and methods were applied and validated in a hypothetical scenario for the synchronous identification of the contamination source and boundary conditions. The results demonstrated that the proposed two-stage inversion framework significantly improved search accuracy compared to single inversion methods, with a mean relative error and mean absolute error of just 4.95% and 0.1756, respectively. Moreover, the multilayer perceptron surrogate model offered greater approximation accuracy to the simulation model than the traditional shallow learning surrogate model. Specifically, the coefficient of determination, mean relative error, mean absolute error, and root mean square error were 0.9860, 9.72%, 0.1727, and 0.47, respectively, highlighting its significant advantages. The findings of this study can provide more reliable technical support for practical case applications and improve subsequent remediation efficiency

Surrogate Model Application to the Identification of Optimal Groundwater Exploitation Scheme Based on Regression Kriging Method—A Case Study of Western Jilin Province

This paper introduces a surrogate model to identify an optimal exploitation scheme, while the western Jilin province was selected as the study area. A numerical simulation model of groundwater flow was established first, and four exploitation wells were set in the Tongyu county and Qian Gorlos county respectively so as to supply water to Daan county. Second, the Latin Hypercube Sampling (LHS) method was used to collect data in the feasible region for input variables. A surrogate model of the numerical simulation model of groundwater flow was developed using the regression kriging method. An optimization model was established to search an optimal groundwater exploitation scheme using the minimum average drawdown of groundwater table and the minimum cost of groundwater exploitation as multi-objective functions. Finally, the surrogate model was invoked by the optimization model in the process of solving the optimization problem. Results show that the relative error and root mean square error of the groundwater table drawdown between the simulation model and the surrogate model for 10 validation samples are both lower than 5%, which is a high approximation accuracy. The contrast between the surrogate-based simulation optimization model and the conventional simulation optimization model for solving the same optimization problem, shows the former only needs 5.5 hours, and the latter needs 25 days. The above results indicate that the surrogate model developed in this study could not only considerably reduce the computational burden of the simulation optimization process, but also maintain high computational accuracy. This can thus provide an effective method for identifying an optimal groundwater exploitation scheme quickly and accurately