The logging-while-drilling (LWD) acoustic logging instrument is pivotal in unconventional oil and gas exploration, and in providing real-time assessments of subsurface formations. The acquisition system, a core component of the LWD acoustic logging suite, is tasked with capturing, transmitting, and processing acoustic signals from the formation, which directly affects the accuracy and timeliness of the logging data. Recognizing the constraints of current LWD acquisition systems, including limited data collection capabilities and inadequate precision, this study introduces an FPGA-based multi-node data acquisition system for LWD acoustic logging.
View Article and Find Full Text PDFRobots are increasingly integral across various sectors due to their efficiency and superior capabilities, which enable performance beyond human potential. However, the development of robotic systems often conflicts with the sustainable development goals set by the United Nations, as they generate considerable nondegradable waste and organic/inorganic pollutants throughout their life cycle. In this paper, we introduce a dual closed-loop robotic system that integrates biodegradable, sustainable materials such as plasticized cellulose films and NaCl-infused ionic conductive gelatin organogels.
View Article and Find Full Text PDFThe MoS/MoO nano-heterojunction photocatalyst was synthesized the oxidation sintering method. The properties of the samples were characterized by XRD, SEM, EDX, TEM, UV-vis, PL, FT-IR, BET and electrochemical techniques. The MoS/MoO nano-heterojunction (MS-400) exhibited significantly better photocatalytic activity toward Rhodamine B degradation (0.
View Article and Find Full Text PDFThe increasing needs for new types of computing lie in the requirements in harsh environments. In this study, the successful development of a non-electrical neural network is presented that functions based on mechanical computing. By overcoming the challenges of low mechanical signal transmission efficiency and intricate layout design methodologies, a mechanical neural network based on bistable kirigami-based mechanical metamaterials have designed.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
August 2023
Identifying efficient and accurate optimization algorithms is a long-desired goal for the scientific community. At present, a combination of evolutionary and deep-learning methods is widely used for optimization. In this paper, we demonstrate three cases involving different physics and conclude that no matter how accurate a deep-learning model is for a single, specific problem, a simple combination of evolutionary and deep-learning methods cannot achieve the desired optimization because of the intrinsic nature of the evolutionary method.
View Article and Find Full Text PDFSensors (Basel)
April 2023
Acoustic logging instruments generate high voltages in the order of thousands of volts. Electrical interferences are thus induced by high-voltage pulses that affect the logging tool and make it inoperable owing to damaged components in severe cases. High-voltage pulses from the acoustoelectric logging detector interfere with the electrode measurement loop through capacitive coupling, which has seriously affected the acoustoelectric signal measurements.
View Article and Find Full Text PDFSensors (Basel)
March 2023
Azimuthal acoustic logging can survey the downhole formation more accurately, and the acoustic source is the crucial component of the downhole acoustic logging tool with azimuthal resolution characteristics. To realize downhole azimuthal detection, assembling multiple transmitting piezoelectric vibrators in the circumferential direction is necessary, and the performance of azimuthal-transmitting piezoelectric vibrators needs attention. However, effective heating test and matching methods are not yet developed for downhole multi-azimuth transmitting transducers.
View Article and Find Full Text PDFUltrasonic imaging logging can visually identify the location, shape, dip angle and orientation of fractures and holes. The method has not been effectively applied in the field; one of the prime reasons is that the results of physical simulation experiments are insufficient. The physical simulation of fracture and hole response in the laboratory can provide a reference for the identification and evaluation of the underground geological structure.
View Article and Find Full Text PDFTo increase the accuracy of reservoir evaluation, a new type of seismoelectric logging instrument was designed. The designed tool comprises the invented sonde-structured array complex. The tool includes several modules, including a signal excitation module, data acquisition module, phased array transmitting module, impedance matching module and a main system control circuit, which are interconnected through high-speed tool bus to form a distributed architecture.
View Article and Find Full Text PDFNanotechnology
January 2021
We propose a valley filter based on 8-Pmmn borophene which hosts two tilted Dirac cones. It is found that the application of a magnetic-electric barrier provided by a single ferromagnetic gate is sufficient to create valley-polarized current in 8-Pmmn borophene. The valley polarization of output current depends on the barrier orientation.
View Article and Find Full Text PDFSensors (Basel)
July 2019
To improve the performance of acoustic logging tool in detecting three-dimensional formation, larger and more complicated transducer arrays have been used, which will greatly increase the difficulty of fault diagnosis during tool assembly and maintenance. As a result, traditional passive diagnostic methods become inefficient, and very skilled assemblers and maintainers are required. In this study, fault-diagnosis requirement for the acoustic logging tool at different levels has been analyzed from the perspective of the tool designer.
View Article and Find Full Text PDFThe ultrafast elastic light scattering technique is applied to reveal the strong nonlinearity of V_{3}O_{5} associated with a photoinduced insulator-metal phase transition. Observation of time-domain relaxation dynamics suggests several stages of structural transition. We discuss the nonequilibrium processes in V_{3}O_{5} in terms of photoinduced melting of a polaronic Wigner crystal, coalescence of V-O octahedra, and photogeneration of acoustical phonons in the low-T and high-T phases of V_{3}O_{5}.
View Article and Find Full Text PDFA logging-while-drilling (LWD) caliper is a tool used for the real-time measurement of a borehole diameter in oil drilling engineering. This study introduces the mechanical structure and working principle of a new LWD caliper based on ultrasonic distance measurement (UDM). The detection range is a major performance index of a UDM system.
View Article and Find Full Text PDFCancer stem cells (CSCs) are commonly associated with cancer recurrence and metastasis that occurs in up to 30-55% of non-small-cell lung carcinoma (NSCLC) patients. Herein, we showed that serine-arginine protein kinase 1 (SRPK1) was highly expressed at both the mRNA and the protein levels in human NCSLC. SRPK1 was associated with the clinical features of human NSCLC, including clinical stage (p < 0.
View Article and Find Full Text PDFBackground: Individuals with autism put a heavy demand on medical services, and prevalence estimates are needed for the planning of such services. Screening for autism in children has important implications for individuals and policy makers. This study aimed to estimate prevalence of suspected autism in children in Longhua District, Shenzhen, and to investigate risk factors for autism.
View Article and Find Full Text PDFHousehold registration status is one social determinant that influences health disparities. This study aimed to investigate the disparities in cardiovascular health between local and migrant residents, which may provide important implications for public health services and may help improve cardiovascular health for residents in Shenzhen.A cross-sectional study was conducted in Shenzhen City Longhua district.
View Article and Find Full Text PDFJ Chem Phys
December 2011
Wave packets in graphene whose central wave vector is at Dirac points are investigated by numerical calculations. Starting from an initial Gaussian function, these wave packets form into annular peaks that propagate to all directions like ripple-rings on water surface. At the beginning, electronic probability alternates between the central peak and the ripple-rings and transient oscillation occurs at the center.
View Article and Find Full Text PDFJ Nanosci Nanotechnol
August 2010
We investigate the electronic transport properties of coupled quantum dots, controlled by local gates on carbon nanotubes. The inter-dot coupling can be tuned from weak to strong by changing gate voltages, and oscillates in short and long period with the distance between two gates. We introduce a one-dimensional scattering model to describe the mechanism of the electron transport through the carbon nanotube quantum dots.
View Article and Find Full Text PDFUsing a first-principles linear response theory, the capacitance of the DNA nucleotides, adenine, cytosine, guanine, and thymine, are calculated. The difference in the capacitance between the nucleotides is studied with respect to conformational distortion. The result suggests that although an alternate current capacitance measurement of a single-stranded DNA chain threaded through a nanogap electrode may not be sufficient to be used as a standalone method for rapid DNA sequencing, the capacitance of the nucleotides should be taken into consideration in any GHz-frequency electric measurements and may also serve as an additional criterion for identifying the DNA sequence.
View Article and Find Full Text PDFPhys Rev Lett
November 2007
We report a theoretical study of the dynamic response of electrons in a metallic nanowire or a two-dimensional electron gas under a capacitively coupled "spot gate" driven by an ac voltage. A dynamic standing Friedel wave (SFW) is formed near the spot gate and near edges and boundaries, analogous to the static Friedel oscillations near defects. The SFW wavelength is controlled by the ac voltage frequency and the device's Fermi velocity, whereby the latter can be measured.
View Article and Find Full Text PDFPhys Rev E Stat Nonlin Soft Matter Phys
April 2005
A computational framework for a moment-based O(N) tight-binding atomistic method is presented, analyzed, and applied to the problem of electronic properties of deformed carbon nanotubes, where N is the number of atoms in the system. The moment-based approach is based on the maximum entropy and kernel polynomial methods for constructing the electronic density of states from local statistical information about the environment around individual atoms. Random-walk statistics are formally presented as the basis for several methods to collect the moments of the density of states in a computationally efficient manner.
View Article and Find Full Text PDFZhongguo Wei Zhong Bing Ji Jiu Yi Xue
December 2003
Objective: Pulmonary artery (PA) catheterization monitoring (Swan-Ganz) is usually not available to critically high-risk surgical patients before admission to ICU, where action to correct values derived from such monitoring may be too late. To explored the effect of non-invasive monitoring systems that allow hemodynamic monitoring during the early stages after trauma.
Methods: The early temporal hemodynamic patterns after high-risk trauma with non-invasive monitoring systems were evaluated, and compared these to invasive PA monitoring.
We investigate electronic transport properties of the squashed armchair carbon nanotubes, using tight-binding molecular dynamics and the Green's function method. We demonstrate a metal-to-semiconductor transition while squashing the nanotubes and a general mechanism for such a transition. It is the distinction of the two sublattices in the nanotube that opens an energy gap near the Fermi energy.
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