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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Characterization of Plasmonic Effects in AuNP+rGO Composite as a Sensing Layer for a Low-cost Lab-on-chip Biosensor
摘要： In this paper, we study the joint pilot assignment and resource allocation for system energy efficiency (SEE) maximization in the multi-user and multi-cell massive multi-input multi-output network. We explicitly consider the pilot contamination effect during the channel estimation in the SEE maximization problem, which aims to optimize the power allocation, the number of activated antennas, and the pilot assignment. To tackle the SEE maximization problem, we transform it into a subtractive form, which can be solved more efficiently. In particular, we develop an iterative algorithm to solve the transformed problem where optimization of power allocation and number of antennas is performed, and then pilot assignment optimization is conducted sequentially in each iteration. To tackle the first sub-problem, we employ a successive convex approximation (SCA) technique to attain a solvable convex optimization problem. Moreover, we propose a novel iterative low-complexity algorithm based on the Hungarian method to solve the pilot assignment sub-problem. We also describe how the proposed solution approach can be useful to address the sum rate (SR) maximization problem. In addition to the algorithmic developments, we characterize the optimal structure of both SEE and SR maximization problems. The numerical studies are conducted to illustrate the convergence of the proposed algorithms, impacts of different parameters on the SR and SEE, and significant performance gains of the proposed solution compared the conventional design.
关键词： Energy efficiency,multi-cell,massive MIMO,power allocation,pilot contamination,pilot assignment
更新于2025-09-23 15:21:01
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Analysis of Salt Mixture Contamination on Insulators via Laser-Induced Breakdown Spectroscopy
摘要： The composition of contamination deposited on transmission line insulators can affect their surface flashover voltage. Currently, there is no rapid on-line method to detect this contamination composition in power grids. In this paper, we applied laser-induced breakdown spectroscopy (LIBS) to analyze contamination on insulator surfaces. Usually, Na and Ca salts are found in contamination along with various sulfate, carbonate, and chloride compounds. As an element’s detection method, LIBS can only measure a certain element content, for example, Ca. The mixture of various compounds with the same cations can influence the LIBS signal. The influence of mixing ratios on the calibration curves and relative spectral intensity was studied via LIBS. Na2CO3, NaHCO3, CaSO4, and CaCO3 samples containing different proportions of Na and Ca were prepared. The linear correlation coefficients (R2) for the Na and Ca calibration curves generated using various mixing ratios were analyzed. The results showed that the mixture ratio did not dramatically affect the linear calibration curves for mixtures containing the same cations. This finding may significantly reduce the difficulty of applying LIBS analysis for complex contamination on insulators. The laser energy density had effects on the spectral characteristics of the measured elements. The partial least-square regression (PLSR) model can improve the accuracy of Na and Ca prediction.
关键词： salt,insulators,calibration curves,laser-induced breakdown spectroscopy,contamination
更新于2025-09-23 15:21:01
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[IEEE SoutheastCon 2018 - St. Petersburg, FL, USA (2018.4.19-2018.4.22)] SoutheastCon 2018 - Updates and Significance of Precision Cleaning and Inspection of Fiber Optic and Hybrid Fiber Optic/Copper Connections Including ‘Military Style’ Round Types
摘要： First published in 1998, standards for inspection and cleaning fiber optic surfaces are based on a two-dimensional understanding of the connector and debris. Of course, these structures are three-dimensional as are all types of associated debris and contamination. There is a “primary surface” as often defined by IEC 61300-3-35. There are also “secondary surfaces” which I coin as Zone-4 and Zone-5 that can be ‘soil points’ unstudied and not considered until this time. This limited understanding may have been more acceptable in 1998 when transmission rates were mere fractions of practical deployments in this time. Over the years, a wide range of inspection and cleaning products, methods and procedures were developed. Some work well, some are outdated; others poorly conceived. There is need for a new ‘future-proof’ understanding for all industry segments. There is need to re-train many thousands of misunderstandings and misimpressions. It’s anecdotally stated that improper cleaning is 60% of ‘network problems’. What was ‘theoretical’ for fiber optics, regularly becomes ‘practical’. Not only are fiber optic connectors advanced into multiple fibers per connector, but also, hybrid connectors contain copper low-voltage and high-voltage termini in close proximity. Smaller connections, ever more difficult to see, also become problematic to clean. Cleaning fiber optic termini is essential: a soiled surface is not unlike looking through a dirty windshield! Connector technology is amazing and outpaces advances within the bookends of standards issued or updated every five to ten years. Military style connectors have advanced and, like SMPTE for broadcast, may be “pure fiber”, or hybrid types with fiber, power, and data transmissions. In recent times, military style connectors have included ‘multiple fiber’ (MT-Types” as well as standard SC/LC. FC and the like. No matter the deployment types, properly cleaning these surfaces assures highest quality transmissions. Cleaning fiber surfaces has evolved to ‘convenience’ rather than practical best practice. For example, it is common to use a ‘dry tool’ to clean ‘dry debris’ when in reality, this process can transfer debris, create a static field that attracts more debris, or (simply) is not effective. In other “real world applications” dry-cleaning is used for a surface that is “wet”! Copper surfaces can gall or fret from repeated insertions: these surfaces can be properly cleaned and inspected. Cleaning and inspection techniques must be updated, re-thought and re-trained to include all connector types. This paper reflects more than two decades of practical experience to consider a new technique to precision clean and inspect fiber optic surfaces that results in 1st time cleaning. This is essential as many connectors are cleaned without benefit of inspection. Although the work is based on more than 2,500 years of established science, it is controversial within the fiber optic community.
关键词： connector,contamination,military style connectors,Zone-5,inspection,hybrid connectors,standards,three-dimensional,fiber optic,Zone-4,precision cleaning
更新于2025-09-23 15:21:01
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Silicon as a ubiquitous contaminant in graphene derivatives with significant impact on device performance
摘要： Silicon-based impurities are ubiquitous in natural graphite. However, their role as a contaminant in exfoliated graphene and their influence on devices have been overlooked. Herein atomic resolution microscopy is used to highlight the existence of silicon-based contamination on various solution-processed graphene. We found these impurities are extremely persistent and thus utilising high purity graphite as a precursor is the only route to produce silicon-free graphene. These impurities are found to hamper the effective utilisation of graphene in whereby surface area is of paramount importance. When non-contaminated graphene is used to fabricate supercapacitor microelectrodes, a capacitance value closest to the predicted theoretical capacitance for graphene is obtained. We also demonstrate a versatile humidity sensor made from pure graphene oxide which achieves the highest sensitivity and the lowest limit of detection ever reported. Our findings constitute a vital milestone to achieve commercially viable and high performance graphene-based devices.
关键词： device performance,supercapacitors,graphene,humidity sensors,silicon contamination
更新于2025-09-23 15:21:01
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The impact of interstitial Fe contamination on n-type Cz-Silicon for high efficiency solar cells
摘要： In this work, we have investigated the impact of interstitial Fe contamination on the effective minority carrier lifetime of n-type Cz silicon bulk material for high efficiency solar cells. The study covers a Fe concentration in the silicon bulk from 3.5 ? 1012 cm-3 to 2.7 ? 1014cm-3. We have added 5 different concentrations (30, 100, 300, 1000 and 3000 ppb) of Fe intentionally to a wet chemical process tank and measured the transfer to the silicon wafer surface mimicking a possible contamination during wet chemical processing. In order to fabricate carrier lifetime test vehicles, the silicon wafer is then passivated with thermal silicon oxide from both sides. The surface contamination is driven into the bulk by mimicking a high temperature process during solar cell manufacturing. Effective minority carrier lifetime is measured at injection levels from 1 ? 1013 cm-3 to 3 ? 1015cm-3. We have fitted the theoretical curve for interstitial Fe derived from the SRH theory to the measured values and extracted the Fe contamination concentration. This value is comparable to the calculated value extracted from the surface contamination measurement. For low level injection (LLI), we extracted the capture cross section for interstitial Fe to be 6.45 ? 10-17 cm/s ? 2.23 ? 10-17 cm/s. The measured Fe contamination levels are used for the conversion efficiency fitting of a n-type bifacial silicon solar cell using QUOKKA simulations. The simulations show that very low Fe contamination concentrations of [Fe]bulk ? 3.5 ? 1012 cm-3 ([Fe]surf ? 6 ? 1010cm-2) already degrade the solar cell efficiency by 10% relative.
关键词： Effective minority carrier lifetime,Interstitial Fe Contamination,QUOKKA simulations,n-type Si Solar cell,High efficiency
更新于2025-09-23 15:19:57
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Optimization of laser-target parameters for the production of stable lithium beam
摘要： A laser ion source coupled with a radio frequency quadrupole linac accelerator is being proposed as a suitable system for the production of a low energy, high-current stable lithium beam. In order to maximize the lithium yield, plasmas generated by laser ablation of different materials based on lithium (Li, LiOH, and LiNbO3) have been characterized by using a Faraday cup and an electrostatic ion analyzer in the time of flight configuration. A wide range of laser power density has been investigated (109–1012 W/cm2) using two Nd:YAG lasers operating at different wavelengths (1064 nm and 532 nm), pulse durations (6 ns and 17 ns), and maximum energies (1400 mJ and 210 mJ). This paper outlines the pros and cons of the investigated materials by studying how the ion energy, yields, and charge state distributions are modified when the laser power density is changed. Considerable attention has been paid to the higher charge states of oxygen, which may occur with the same mass-to-charge ratio of Li3+. The analysis has evidenced that LiNbO3 represents a valid target since it allows minimizing the O6+/7Li3+ ratio down to 2.5% by using a laser power density of 1.8 × 1010 W/cm2. For such a condition, a Li3+ current of 1.4 mA/cm2 has been measured.
关键词： oxygen contamination,laser ion source,lithium beam,charge state distributions,laser ablation
更新于2025-09-23 15:19:57
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[IEEE 2019 First International Conference of Intelligent Computing and Engineering (ICOICE) - Hadhramout, Yemen (2019.12.15-2019.12.16)] 2019 First International Conference of Intelligent Computing and Engineering (ICOICE) - An Efficient Implementation of LED Block Cipher on FPGA
摘要： The cold calibration count from the Advanced Technology Microwave Sounder (ATMS) space view increases when the lunar radiation intrudes its antenna field of view (FOV). This increase is referred to as lunar contamination since the cold count is not matched with the specified brightness temperature of 2.73 K. For ATMS, it is found that the elapse time of lunar intrusion (LI) and the magnitude of the cold count increase are channel dependent. If the lunar-affected calibration counts are rejected in the processing, a data gap can be shown in brightness temperature at all channels. At ATMS channels 1 and 2, which have a large FOV, the LI can result in an increase of 40 counts in cold calibration. At higher frequency channels which have a smaller FOV size, the LI intensity is much stronger and can be as large as a few hundred counts. The LI becomes significant when its radiation appears in the ATMS antenna main beam. In the current ATMS operational calibration algorithm, the cold count anomaly is detected when the intensity of LI exceeds a certain threshold. The lunar radiation can be also corrected in the ATMS calibration. In doing so, a lunar radiation term is derived as a function of antenna gain, the solid angle of the Moon, and the brightness temperature of the Moon disk. This algorithm is applied in an ATMS calibration system developed at NOAA and shows a successful removal of all the lunar contamination on the earth-scene brightness temperature.
关键词： Advanced Technology Microwave Sounder (ATMS),contamination,lunar intrusion (LI),calibration
更新于2025-09-23 15:19:57
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Annals of Computer Science and Information Systems [IEEE 2019 Federated Conference on Computer Science and Information Systems - (2019.9.1-2019.9.4)] Proceedings of the 2019 Federated Conference on Computer Science and Information Systems - Improving Real-Time Performance of U-Nets for Machine Vision in Laser Process Control
摘要： This paper considers a multi-cell network with base stations (BSs) equipped with large dual-polarized antenna arrays. We derive closed-form expressions of network performance in terms of user signal-to-interference-and-noise ratio both with perfect channel state information and in the presence of pilot contamination. In general, a dual-polarized system enjoys the reduction in pilot contamination and multiuser interference due to orthogonal polarizations, while the available BS array dimension is reduced in each polarized direction compared with a monopole antenna setup. The derived results, however, reveal that the performance of a dual polarization system can be optimized by properly setting receive antenna polarizations, and fortunately, the optimal performance behaves identically to that of a monopole-antenna one in massive MIMO. We ?nally verify the observations by numerical simulations.
关键词： dual-polarized antenna,multi-cell,pilot contamination,channel capacity,Massive MIMO
更新于2025-09-23 15:19:57
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Influence of Sample Mixing Techniques on Engine Oil Contamination Analysis by Infrared Spectroscopy
摘要： For the most reliable and reproducible results for calibration or general testing purposes of two immiscible liquids, such as water in engine oil, good emulsi?cation is vital. This study explores the impact of emulsion quality on the Fourier transform infrared (FT-IR) spectroscopy calibration standards for measuring water contamination in used or in-service engine oil, in an attempt to strengthen the speci?c guidelines of ASTM International standards for sample preparation. By using different emulsi?cation techniques and readily available laboratory equipment, this work is an attempt to establish the ideal sample preparation technique for reliability, repeatability, and reproducibility for FT-IR analysis while still considering the ease and ef?ciency of the technique. This study demonstrates that a stable emulsion within a sample, which depends heavily upon the method, provides a reliably consistent homogenous sample for quanti?cation purposes with FT-IR analysis. Analysis of variance (ANOVA) modeling and limit of detection calculations demonstrate the stability of the emulsion. The results reveal that setting a mixing time for a calibration standard depends on the emulsi?cation process. Inserting a probe directly into a sample (direct sonication) allows for a rapid, stable emulsion with high reproducibility. Indirect sonication produces relatively non-miscible liquids of different densities. The pan-shaker produces a reasonably stable emulsion, but without the long-term stability or quick production time of direct sonication. Reaction time plays a critical role in the rotary mixing method, which leads to a slow development of emulsi?cation.
关键词： mixing methods,lubricating oils,emulsion,water contamination,infrared spectroscopy
更新于2025-09-19 17:15:36
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Compact Trible-band Microstrip BPF Utilizing Interdigital-coupled Lines Feeding Structure
摘要： In this paper, we study the joint pilot assignment and resource allocation for system energy efficiency (SEE) maximization in the multi-user and multi-cell massive multi-input multi-output network. We explicitly consider the pilot contamination effect during the channel estimation in the SEE maximization problem, which aims to optimize the power allocation, the number of activated antennas, and the pilot assignment. To tackle the SEE maximization problem, we transform it into a subtractive form, which can be solved more efficiently. In particular, we develop an iterative algorithm to solve the transformed problem where optimization of power allocation and number of antennas is performed, and then pilot assignment optimization is conducted sequentially in each iteration. To tackle the first sub-problem, we employ a successive convex approximation (SCA) technique to attain a solvable convex optimization problem. Moreover, we propose a novel iterative low-complexity algorithm based on the Hungarian method to solve the pilot assignment sub-problem. We also describe how the proposed solution approach can be useful to address the sum rate (SR) maximization problem. In addition to the algorithmic developments, we characterize the optimal structure of both SEE and SR maximization problems. The numerical studies are conducted to illustrate the convergence of the proposed algorithms, impacts of different parameters on the SR and SEE, and significant performance gains of the proposed solution compared the conventional design.
关键词： Energy efficiency,multi-cell,massive MIMO,power allocation,pilot contamination,pilot assignment
更新于2025-09-19 17:13:59