Low-Cost Waste Management Solutions for Small-to-Medium Scale Pig Farms in China

Within the last several years, the Chinese government has implemented strict new waste management regulations for Chinese pig farms. Our project team has partnered with a rural pig farmer, Mr. Zhu, in Anhui Province, China. Our team will research and recommend environmentally and financially sustainable waste management solutions that will help Mr. Zhu’s farm remain compliant. During a summer 2018 assessment trip, we found inadequate storage capacity for pig slurry and issues of wastewater runoff. We also conducted a local community survey and found that local residents are concerned with odor and wastewater runoff from the farm. We will design a treatment system for Mr. Zhu to address these issues by the end of 2018. The library mini-grant will help fund a follow-up trip in summer 2019, during which we will assess and evaluate the solutions that Mr. Zhu will have implemented. We will also conduct a follow-up community survey to confirm that broader community concerns have been addressed.DOW Sustainability granthttps://deepblue.lib.umich.edu/bitstream/2027.42/148849/1/Liu.pd

Improving Building Sustainability: Lighting Life Cycle Optimization and Management, and HVAC Demand Response

Residential and commercial buildings represent 39% of global energy carbon emissions. In the U.S., buildings consume 40% of the total energy consumption and thus represent a substantial energy saving opportunity. Additionally, building energy flexibility, or the ability to reduce or move demand to a different time, is playing an increasingly important role in grid modernization and renewable integration by helping to balance supply. Material efficiency is another foundation to sustainability, as many energy-efficient and renewable technologies depend on the use of specialty materials, which are dwindling in supply and many face geopolitical conflicts. This dissertation advances methods of life cycle analysis and data analytics while addressing some of these issues and opportunities in three key aspects – how to choose better products, how to better manage products at their end of life, and how to use energy more effectively. Chapter 2 and 3 examine the keep vs. replace conundrum by studying the replacement of residential and commercial lighting, in which the rapidly changing LED technology creates unclear tradeoffs with incumbent lighting in terms of cost, energy savings, and emissions. The results suggest that while LED lighting offers competitive performance and life cycle cost as fluorescent lighting, there is less advantage (or benefit) for immediate LED adoption in a lower use, upfront cost-sensitive, or slowly decarbonizing grid situation. Chapter 4 evaluates the life cycle impacts of recovering rare earth and critical metals from spent linear fluorescent and LED fixtures, respectively. This chapter also assesses the impacts of extended use and modular (component) replacement to assess the value of reverse logistics (reuse, remanufacturing, and recycling). The results show that both types of metal extraction create net environmental impacts, which can be mitigated with process optimization and waste preprocessing to increase extraction efficiency. While modular replacement leads to overall lower environmental burdens, full replacement can offer incentive for LED recycling as their metal-heavy housing structure and heat sink are attractive to recyclers. Chapter 5 performs piecewise log-linear-Fourier regressions on whole-home smart meter data and outdoor temperature data to disaggregate the thermostatically controlled loads from whole-home consumption and to estimate the technical thermal demand response potentials in the Midwest. The results suggest that single family buildings, being the higher energy users and larger customer base than multi-family, can provide higher per customer and aggregated demand flexibility. However, multi-family buildings, particularly those with a central HVAC system, may have the advantage of pooled demand across multiple units and should therefore be considered accordingly. By examining the three decision-making questions related to technology and product selection (Chapter 2 - 3), waste management and material recovery (Chapter 4), and energy use and demand response (Chapter 5), the research helps inform decision making for building managers and energy consumers, and provide industry with insights regarding product design, reverse logistics, and demand response program recruitment.PHDMech Eng & Nat Res Env PhDUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/163086/1/lixiliu_1.pd

Forget metamaterial: It does not improve sound absorption performance as it claims

The term `sub-wavelength' is commonly used to describe innovative sound-absorbing structures usually labeled as `metamaterials'. Such structures, however, inherently do not bring groundbreaking advancements. This study addresses the limitations imposed by the thickness criterion of Yang et al. by introducing the concept of equivalent mass-spring-damping parameters within the resonator framework. This innovative approach introduces an index of `half-absorption bandwidth' to effectively overcome the thickness restriction. Four practical cases are then presented to correct prevalent misleading conceptions about low-frequency, broadband absorption as claimed. The phenomenon of mass disappearing in the expression of sound absorption coefficient supports the conclusion that volume is the only determinant factor in sound absorption performance. Any attempts to improve sound absorption solely through geometry and structural designs would inevitably sacrifice the half-absorption bandwidth. Additionally, the concept of negative stiffness or bulk modulus is merely a mathematical convention without any real improvement in absorption performance. Overall, this research focuses on the physical mechanism of sound-absorbing structures by correcting traditional misunderstandings, and offers a comprehensive framework for assessing and enhancing sound absorption.Comment: 12 pages, 5 figures, part of the first author's Ph.D. thesi

Fault slippage and its permeability evolution during supercritical CO2 fracturing in layered formation

International audienceUnderstanding the hydromechanical responses of faults during supercritical CO2 fracturing is important for reservoir management and the design of energy extraction systems. As small faults are widespread in Chang 7 member of the Yanchang Formation, Ordos Basin, China, supercritical CO2 fracturing operation has the potential to reactive these undetected small faults and leads to unfavorable fracking fluid migrate. In this work, we examined the role of fault slippage and permeability evolution along a small fault connecting the pay zone and the confining formation during the whole process of fracturing and production. A coupled hydromechanical model conceptualized from actual engineering results was introduced to address the main concerns of this work, including, (1) whether the existence of a undetected small fault would effectively constrain the hydraulic fracture height evolution, (2) what the magnitude of the induced microseismic events would be and (3) whether the permeability change along the fault plane would affect the vertical conductivity of the confining formation and thus increase the risk for the fracturing fluid to leak. Our results have shown that the initial hydrofracture formed at the perforation and propagated upward, once it merged with the fault surface, the existence of an undetected small fault would effectively constrain the hydraulic fracture height evolution. As fracturing continued, further slippage spread from the permeability increase zone of high permeability to shallower levels, and the extent of this zone was dependent on the magnitude of the fault slippage. At the end of extraction, the slip velocity decreases gradually to zero and the fault slippage finally reaches stabilization. In general, undetected small faults in targeted reservoir may not be the source of large earthquakes. The induced microseismic events could be considered as the sources of acoustic emission events detected while monitoring the fracturing fluid front. Due to the limited fault slippage and lower initial permeability, the CO2 fracturing operation near undetected small faults could not conduct preferential pathway for upward CO2 leakage or contaminate overlying shallower potable aquifers

The influence of water-based drilling fluid on mechanical property of shale and the wellbore stability

AbstractBecause of high cost and pollution of oil-based drilling fluid, the water-based drilling fluid is increasingly used now. However, bedding planes and micro-cracks are rich in shale formation. When water-based drilling fluid contacts formation rock, it causes the propagation of crack and invasion of drilling fluid, which decrease shale strength and cause wellbore instability. In this paper, we analyzed influence of water-based drilling fluid on shale strength and failure mode by mechanics experiment. Based on those experimental results, considering the effect of bedding plane and drilling time, we established modeling of wellbore stability for shale formation. The result from this model indicates that in certain azimuth of horizontal well, collapsing pressure increases dramatically due to shale failure along with bedding plane. In drilling operation, those azimuths are supposed to be avoided. This model is applicable for predication of collapsing pressure in shale formation and offers reference for choosing suitable mud weight

Prediction of mechanical parameters for low-permeability gas reservoirs in the Tazhong Block and its applications

 A longitudinal distribution profile of the mechanical properties of the formations is important for the safe drilling, successful completion, and development of oil and gas reservoirs. However, the mechanical profile of the carbonate formations from the low-permeability gas reservoirs in the Tazhong (TZ) Block is hard to achieve due to the complex structural and lithological characteristics of the carbonates. In this paper, lab measurements are carried out to determine the physical and mechanical properties of the carbonate rocks of the Yingshan Formation in the TZ Block. Based on this, the relationships among density, the interval transit time and the mechanical parameters of the rocks in the TZ Block are constructed. The constructed relationships are then applied to the well-logging prediction of the mechanical profiles of the carbonate formations. The models are verified through the application to the two wells in the TZ Block, the results show that the relative errors in the predicted mechanical parameters are within 10% indicating the efficiency of the constructed models. The result of this study provides reasonable mechanical parameters for the exploration and development of the carbonate reservoirs in the TZ Block.Cited as: Wan, Y., Zhang, H., Liu, X., Yin, G., Xiong, J., Liang, L. Prediction of mechanical parameters for low-permeability gas reservoirs in the Tazhong Block and its applications. Advances in Geo-Energy Research, 2020, 4(2): 219-228, doi: 10.26804/ager.2020.02.1

The Similar Structure Method for Solving the Model of Fractal Dual-Porosity Reservoir

This paper proposes a similar structure method (SSM) to solve the boundary value problem of the extended modified Bessel equation. The method could efficiently solve a second-order linear homogeneous differential equation’s boundary value problem and obtain its solutions’ similar structure. A mathematics model is set up on the dual-porosity media, in which the influence of fractal dimension, spherical flow, wellbore storage, and skin factor is taken into cosideration. Researches in the model found that it was a special type of the extended modified Bessel equation in Laplace space. Then, the formation pressure and wellbore pressure under three types of outer boundaries (infinite, constant pressure, and closed) are obtained via SSM in Laplace space. Combining SSM with the Stehfest algorithm, we propose the similar structure method algorithm (SSMA) which can be used to calculate wellbore pressure and pressure derivative of reservoir seepage models clearly. Type curves of fractal dual-porosity spherical flow are plotted by SSMA. The presented algorithm promotes the development of well test analysis software

Is routine drainage necessary after thyroid surgery? A randomized controlled trial study

ObjectiveTo evaluate whether no drainage has an advantage over routine drainage in patients with thyroid carcinoma after unilateral thyroid lobectomy and central neck dissection.MethodsA total of 104 patients with thyroid cancer who underwent unilateral thyroid lobectomy and central lymph node dissection were randomly assigned into no drainage tube (n=52) and routine drainage tube (n=52) placement groups. General information of each patient was recorded, including the postoperative drainage volume/residual cavity fluid volume, postoperative complications, incision area comfort, and other data, and the thyroid cancer-specific quality of life questionnaire (THYCA-QoL) and patient and observer scar assessment scale (POSAS) were evaluated after surgery. At the 3–6 month follow-up exam, the differences between the two groups were compared based on univariate analysis.ResultsSignificant differences were not observed in the general and pathological information (including sex, age, body weight, body mass index (BMI), incision length, specimen volume, Hashimoto’s thyroiditis, and number of lymph nodes dissected), operation time, and postoperative complications (postoperative bleeding, incision infection, lymphatic leakage, and temporary hypoparathyroidism) between the two groups. The patients in the non-drainage group had a shorter hospital stay (2.11 ± 0.33 d) than the patients in the drainage group (3.38 ± 0.90 d) (P<0.001). The amount of cervical effusion in patients in the non-drainage group (postoperative 24h: 2.20 ± 1.24 ml/48 h: 1.53 ± 1.07 ml) was significantly less than that in the drainage group (postoperative 24 hours: 22.58 ± 5.81 ml/48 h: 36.15 ± 7.61 ml) (all P<0.001). The proportion of incision exudation and incision numbness in the non-drainage group was lower than that in the drainage group (all P<0.05), and the pain score (VAS) and neck foreign body sensation score (FBST) decreased significantly (P<0.05). During the 3- and 6-month follow-up exams, significant differences were not observed between the THYCA-QoL and drainage groups and the non-drainage group, although the scarring and POSAS values were lower than those in the drainage group. In addition, the length of stay and cost of hospitalization in the non-drainage group were lower than those in the drainage group (P<0.05).ConclusionRoutine drainage tube insertion is not needed in patients with unilateral thyroid lobectomy and central neck dissection

Colorimetric Assay for Determination of Lead (II) Based on Its Incorporation into Gold Nanoparticles during Their Synthesis

In this report, we present a new method for visual detection of Pb2+. Gold nanoparticles (Au-NPs) were synthesized in one step at room temperature, using gallic acid (GA) as reducer and stabilizer. Pb2+ is added during the gold nanoparticle formation. Analysis of Pb2+ is conducted by a dual strategy, namely, colorimetry and spectrometry. During Au-NPs synthesis, addition of Pb2+ would lead to formation of Pb-GA complex, which can induce the aggregation of newly-formed small unstable gold nanoclusters. Consequently, colorimetric detection of trace Pb2+ can be realized. As the Pb2+ concentration increases, the color turns from red-wine to purple, and finally blue. This method offers a sensitive linear correlation between the shift of the absorption band (Δλ) and logarithm of Pb2+ concentration ranging from 5.0 × 10−8 to 1.0 × 10−6 M with a linear fit coefficient of 0.998, and a high selectivity for Pb2+ detection with a low detection limit down to 2.5 × 10−8 M

Energy Down-Conversion Cs3Cu2Cl5 Nanocrystals for Boosting the Efficiency of UV Photodetector

Zero-dimension (0-D) lead halide perovskite nanocrystals (NCs) have attracted a sight of interest in the field of optoelectronic devices due to their outstanding properties, such as high photoluminescence quantum yield (PLQY) and size- and composition-controlled tunable emission wavelengths. However, the toxicity of lead (Pb) element in the lead perovskite NCs is the bottleneck for the commercial application of perovskite NCs. Herein, we report a facile ligand-assisted synthesis to achieve lead-free Cs3Cu2Cl5 NCs with a high PLQY of ∼70% and good stability against environmental oxygen/moisture as a promising down-conversion material. It has good merits of high PLQY and large Stokes shift (∼300 nm) originated from the effect of Jahn–Teller distortion and self-trapped excitons (STEs). Furthermore, the Cs3Cu2Cl5 NCs embedded composite films (NCCFs) were utilized to enhance the ultraviolet (UV) response of silicon (Si) photodetectors. External quantum efficiency (EQE) measurements show that the UV response can be greatly improved from 3.3 to 19.9% @ 295 nm based on NCCFs combined with Si photodiodes. Our work offers an effective approach to develop highly efficient and stable lead-free Cs3Cu2Cl5 NCs for the application in the solar-blind UV photodetector