Browsing by Author "Lu, Jun"
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- An acoustic micro-transmitter enabling tracking of sensitive aquatic species in riverine and estuarine environmentsDeng, Zhiqun Daniel; Li, Huidong; Lu, Jun; Xiao, Jie; Myjak, Mitchell J.; Martinez, Jayson J.; Wang, Yuxing; Zhang, Jiguang (2021-05-19)Conservation of aquatic species requires in-depth understanding of their movement and behavior and their interactions with man-made hydraulic structures. Acoustic telemetry is a primary method to remotely track in 3 dimensions (3D) aquatic animals implanted with transmitters. The transmitter's weight and size are the major limiting factors because the transmitter should not affect the animals' natural behavior. Here, we present an acoustic micro-transmitter that weighs 0.08 g in air, only 1/3 that of existing technologies. The transmitter offers a source level of 148 dB (reference: 1 mu Pa at 1 m) and a service life of 30 days at a 5-s transmission rate. Nearly 100% of tagged fish were detected in field studies, demonstrating the viability of this technology for studying species of early life stages. Information resulting from the use of this technology provides valuable insight for ecological and environmental policy making and resource management worldwide.
- Information-seeking Behavior of International Graduate Students vs. American Graduate Students: A User Study at Virginia Tech 2005Liao, Yan; Finn, Mary; Lu, Jun (ACRL Publications, 2007-01)This is a comparative study on information needs and information-seeking behavior of international graduate students and American graduate students. This user study is based on empirical data collected from an online survey conducted between April 7 and May 28, 2005, at Virginia Tech. The goal of this comparative study is to investigate how graduate students from diverse ethnic groups discover, select, and use various information sources and to obtain insights into international graduate students' information-seeking behavior, especially its similarities and differences compared with the information-locating patterns used by their American peers.
- Inorganic and organic geochemistry of the zinc ores of the Idol Mine, East TennesseeLu, Jun (Virginia Tech, 1993-06-05)The Idol Mine, operated by Clinch Valley Mining Company, is located at the southern end of the Copper Ridge District in Northeastern Tennessee. It is a relatively typical carbonatehosted zinc (Mississippi valley Type) deposit. The ores occur as interfragmental fillings within carbonate breccia bodies of the Lower Ordovician Kingsport and Mascot formations. The paragenesis study reveals that sphalerite, the only zinc mineral, precipitated at the earliest stage of ore formation accompanied by minor amounts of dolomite and marcasite. A major stage of coarse white dolomite precipitation took place after sphalerite. Minor amounts of other gangue minerals including pyrite, calcite, quartz, gypsum and fluorite all postdate ore formation. Field observations complemented by macro- and micro-scale examination of polished sections and doubly-polished thin sections reveal that five alternating light and dark growth bands are distinguishable within sphalerite and are correlatable throughout the mine. Electron microprobe analyses across the growth zones of the sphalerite reveal that the dark A, C, and E bands are characterized by relatively high Cd, Cu and Pb content and the light B and D bands by relatively high Fe content. It is also noted that there are two types of host breccias, one with bleached rims and the other without. Early bleach rimmed breccias are most likely the relics of karst-related breccias and later non-bleached breccias appears to be of tectonic origin. Representative sphalerite, gangue dolomite and host dolostone breccias have been sampled and tested by mass spectrometry to determine the presence and nature of hydrocarbons. The GC/MS analyses reveal that all the samples examined contain aliphatic hydrocarbons with minor amounts of aromatic compounds. The aliphatic hydrocarbons range from C₂₁H₄₄ to C₃₃H₆₈ and are most likely of terrestrial plant origin. On the basis of new observations combined with previous data, a model involving the mixing of two distintive fluids is proposed to account for the formation of the Idol zinc mine.
- Lab-on-a-Fish: Wireless, Miniaturized, Fully Integrated, Implantable Biotelemetric Tag for Real-Time In Vivo Monitoring of Aquatic AnimalsYang, Yang; Lu, Jun; Pflugrath, Brett D.; Li, Huidong; Martinez, Jayson J.; Regmi, Siddhartha; Wu, Bingbin; Xiao, Jie; Deng, Zhiqun Daniel (IEEE, 2022-07-01)In vivo electronic monitoring systems for underwater applications are promising technologies for obtaining information about aquatic animals. State-of-the-art devices are constrained by limits on the number of integrated sensors, large dimensions and weight, and short device longevity. Here, we report the Labon-a-Fish: the world's first biotelemetry tag that combines edge computing with wireless sensing of in vivo physiology [electrocardiogram (ECG) and electromyogram (EMG)], behavior [activity level and tail beat frequency (TBF)], and ambient environment (temperature, pressure, and magnetic field). The Lab-on-a-Fish has a miniaturized form (dry weight: 2.4 g; wet weight: 0.8 g; and dimensions: 5.5 mm x 6.5 mm x 37 mm) for studying small animals. Engineering efforts spanning improvements in battery chemistry, electronic circuit efficiency, and power-saving algorithms extend the longevity of the device to as much as eight months. The designed piezoelectric transducer and its driving circuit enable underwater wireless communication of multiplexed digital sensor data over a distance up to 400 m. The Lab-on-a-Fish can also store the raw data using flash memory for use in locations that are challenging for acoustic communications or when more complex data postprocessing is needed. Long-term in vivo validation in three species-rainbow trout (Oncorhynchus mykiss), white sturgeon (Acipenser transmontanus), and walleye (Sander vitreus)-demonstrated the device's sensing potential for biological and environmental applications.
- Petroleum coke slags: characterization and dissolutionLu, Jun (Virginia Tech, 1997-05-05)Slags are crystalline to vitreous by-product materials generated in many high temperature industrial processes. This study presents a general technique for the identification of the phases present in petroleum coke gasification slags. documents the phase assemblages and textures, and finally determines the dissolution of vanadium from these slags as part of the considerations of potential resource reclamation. The general identification procedure utilizes (1) recognition of separate phases using optical microscopy and scanning electron microscopy; (2) electron probe microanalysis (EPM) of chemical compositions of individual phases; (3) statistical analysis of the EPM data to eliminate spurious data; (4) estimation of valence states of transition metals using thermodynamic and computational methods; (5) derivation of chemical formulae for the phases using computational methods and chemistry of ionic substitutions; (6) verification of phase identity using X-ray diffraction analysis. More than twenty phases were determined in petroleum coke slags including oxides, silicates. vanadates, sulfate. sulfides and alloys. The reduced slags are rich in V₂>0₃ with silicates and minor amounts of sulfides and native metals whereas the oxidized slags are composed of V₂>0₄, nickel aluminum spinels. various vanadates and glass. Textural analysis provided information on the crystallization process, reaction with gasifier refractory lining materials, sulfide exsolution processes, glass devitrification. and the development of chemical zonation in some spinels. This information offers some perspectives on the potential of resource reclamation. Resource reclamation for petroleum coke slags is best assessed with a knowledge of phases, phase assemblages, textures and dissolution behavior of the material. The dissolution of vanadium. the most significant element. was examined using long term dissolution experiments. These demonstrate that vanadium concentrations are pH dependent ranging from 1500 ppm to 5000 ppm with a minimum concentration near pH 6. Vanadium dissolution rates range from L28xlO⁴ mol m² sec⁻¹ to 3.08xlO-6 mol m² sec⁻¹. In view of the strategic nature of vanadium and the fact that the concentration of vanadium in slags is almost two orders of magnitude higher than the current mining grades, petroleum coke slags offer significant potential to serve as resources for vanadium.
- A Real-Time Underwater Acoustic Telemetry Receiver With Edge Computing for Studying Fish Behavior and Environmental SensingYang, Yang; Elsinghorst, Robbert; Martinez, Jayson J.; Hou, Hongfei; Lu, Jun; Deng, Zhiqun Daniel (IEEE, 2022-09)Underwater acoustic telemetry has emerged as a powerful tool for practical applications, including resource exploration, environmental monitoring, and aquatic animal tracking. However, current acoustic telemetry systems lack the capability to transmit the collected data continuously in real time, primarily because the acoustic networking bandwidth is limited. Retrieval of the recorded measurements from the deployed receivers usually must be manual, leading to long delays in data retrieval and processing, high operational costs associated with the required manpower, and safety risks for the operators. In addition, there is no efficient way to continuously assess the status of the acoustic telemetry system, including the acoustic transmitters and receivers. Here, we describe the design, implementation, and field validation of a cloud-based, real-time, underwater acoustic telemetry system with edge computing for estimating fish behavior and monitoring environmental parameters. The system incorporates microcontrollers for edge computing and connects to a cloud-based service that further post-processes the transmitted data stream to derive behavior and survival information of tagged animals. The developed system has been demonstrated to have significantly improved performance over the benchmark system because of the integration of edge computing, with a greatly reduced energy consumption of 0.014 W resulting in the energy used by the acoustic modem being reduced by over 300 times. This work opens up new design opportunities for future real-time and multifunctional underwater acoustic systems.