This study investigated the conversion of cellulose from rice husk (RH) and straw (RS), two types of agricultural waste, into Carboxymethyl cellulose (CMC). Cellulose was extracted using KOH and NaOH, hydrolyzed, and bleached to increase purity and fineness. The cellulose synthesis yielded a higher net CMC content for RH-CMC (84.8%) than for RS-CMC (57.7%). Due to smaller particle sizes, RH-CMC exhibited lower NaCl content (0.77%) and higher purity. FT-IR analysis confirmed similar functional groups to commercial CMC, while XRD analysis presented a more amorphous structure and a higher degree of carboxymethylation. A biodegradable film preparation of starch-based CMC using citric acid as a crosslinking agent shows food packaging properties. The biodegradable film demonstrated good swelling, water solubility, and moisture content, with desirable mechanical properties, maximum load (6.54 N), tensile strength (670.52 kN/m2), elongation at break (13.3%), and elastic modulus (2679 kN/m2), indicating durability and flexibility. The RH-CMC film showed better chemical and mechanical properties and complete biodegradability in soil within ten days. Applying the biodegradable film for tomato preservation showed that wrapping with the film reduced weight loss more efficiently than dip coating. The additional highlight of the work was a consumer survey in Thailand that revealed low awareness but significant interest in switching to alternative uses, indicating commercial potential for eco-friendly packaging choices and market opportunities for sustainable materials.

In recent decades, buried flexible corrugated metal culverts (CMCs) and corrugated metal pipes (CMPs) have increasingly contributed to the development of infrastructure networks. The primary design aspect of these structures is the soil-structure interaction under different modes of loading. Surface static loading caused by traffic flow frequently leads to the development of deformations and internal forces in buried structures. Thus, the investigation of the soil-structure interaction mechanism under surface static loading can yield a deeper understanding of the culvert response, to enhance current design approaches. Furthermore, to assure their continued serviceability over time, the regular inspection of in-service culverts is vital to assess their status in terms of potential damage and material deterioration due to aging factors such as corrosion and/or mechanical abrasion. In this study, laboratory tests were used to monitor the performance of buried flexible open-bottom arch corrugated metal culverts under surface static loading. Following the backfilling of soil surrounding each culvert, surface static loading was initiated via a top loading steel plate. Impacts of the soil cover depth and culvert condition (i.e., intact or deteriorated) were investigated via three test configurations: an intact culvert with a cover depth of 600 mm (C-01), an intact culvert with a cover depth of 300 mm (C-02), and a deteriorated culvert with a cover depth of 300 mm (C-03). During each static loading test, the load-settlement curve of the top loading steel plate, the increase in vertical soil stresses, and culvert deformations and internal forces were recorded. Furthermore, 3D finite element models of the three test configurations were developed by simulating the culvert responses to surface static loading, and the numerical modelling results were then validated against the laboratory measurements. In addition, to investigate the impact of culvert deterioration on the performance of the soil-culvert interaction, numerical models were used to simulate different damage scenarios.

We develop a Bayesian model to predict the maximum thickness of seasonally frozen ground (MTSFG) using historical air temperature and precipitation observations. We use the Stefan solution and meteorological data from 11 stations to estimate the MTSFG changes from 1961 to 2016 in the Yellow River source region of northwestern China. We employ an antecedent precipitation index model to estimate changes in the liquid soil water content. The marginal posterior probability distributions of the antecedent precipitation index parameters are estimated using Markov chain Monte Carlo sampling methods. We compare the results of our stochastic method with those obtained from the traditional deterministic method and find that they are consistent in general. The stochastic approach is effective for estimating the historical changes in the frozen ground depth (root-mean-square errors = 0.13-0.35 m), and it provides more information on model uncertainty regarding soil moisture variations. Additionally, simulation shows that the MTSFG has decreased by 0.31 cm per year over the last 56 years on the northeastern Qinghai-Tibet Plateau. This decrease in frost depth accelerated in the 1990s and 2000s. Considering the lack of data on seasonally frozen soil monitoring, the Bayesian method provides a pragmatic approach to statistically model frozen ground changes using available meteorological data.

天文导航系统是典型的非线性和噪声非高斯分布的系统。针对传统的扩展卡尔曼滤波不适于非线性和噪声非高斯分布的系统,和一般粒子滤波存在的粒子退化等问题,提出了一种将RJMCMC(可逆跳转马尔可夫链蒙特卡罗)算法应用于月球探测器自主天文导航粒子滤波器中的新方法。计算机仿真结果显示了该方法在加快收敛速度、提高导航定位精度和自适应调整粒子个数方面的有效性和可行性。