High Splitting Ratio Research Articles

On-Chip Droplet Splitting with High Volume Ratios Using a 3D Conical Microstructure-Based Microfluidic Device.

This work reports a simple microfluidic method for splitting a mother droplet into two daughter droplets with high and precise volume ratios. To achieve this, a droplet-splitting microfluidic device embedded with a three-dimensional (3D) conical microstructure is fabricated, in which the high splitting ratios of monodisperse mother droplets are achieved. The volume ratio of the split daughter droplets can reach up to 265. In addition, we examined factors that affect the splitting ratio of the daughter droplets and found that the ratio is affected by the flow rates of the two individual outlet channels, the injection length of the conical microstructure, and the diameter of the original mother droplets. Numerical simulations of these parameters were conducted to gain a clearer understanding of the splitting behavior. The proposed droplet splitting device with a conical microstructure enables on-chip sample extraction and droplet volume control, which can be a powerful tool for various droplet-based applications in microfluidic devices such as viral infectivity assays and sequencing heterogeneous populations.

Investigation of the recompression pathway in the supercritical CO2 Brayton cycle: Cycle modification and thermodynamic study

The recompression process in supercritical CO2 (S-CO2) Brayton cycle is highly energy-intensive, leading to significant temperature rises and complex interactions with internal regeneration and overall cycle performance. This paper aims to investigate the influence of recompression path selection on S-CO2 Brayton cycle and explores opportunities to improve cycle performance by varying the recompression intake position. To actively regulate recompression inlet temperature, two modified layouts based on the conventional recompression S-CO2 Brayton cycle are proposed. Detailed energy and exergy analyses are conducted for these cycles. Optimization is then conducted for modified cycles under different operation conditions to find the optimal recompression path. Thermal efficiency maps with variation of key variables are depicted among cycles to give a comparative evaluation for recompression path selection. The results show that the modified recompression cycles could overtake conventional cycle in thermal efficiency under various certain operation conditions. At split ratio lower than 0.5, further precooling before recompression enhances thermal efficiency. In a case study, thermal efficiency is improved from 39.1 % to 41.7 %. Efficiency of modified cycle becomes less sensitive to main compressor inlet parameters. The modification of three-stage recuperation is effective to eliminate inner pinch point during recuperation and enhance cycle efficiency, with a proper higher recompression inlet temperature. At higher split ratio, shifting recompression path could bring benefits, with a maximum thermal efficiency increasing from 41.6 % to 43.6 % in the case study. Efficiency deterioration could be mitigated by reasonably changing recompression path in off-design operation.

Analysis of the Influence of the Announcement of Stock Splits on Insider Trading Indicators in the Indonesian Stock Exchange Environment for the 2013-2023 Period

The phenomenon of stock split is a corporate action to increase the number of shares outstanding in the market with the aim of making the stock price more affordable for investors. This practice is often carried out by company management to enhance stock liquidity and attract investor interest without necessarily increasing net income. However, although Stock Splits are generally considered a positive policy, some studies indicate that in some cases, Stock Splits can be exploited for insider trading activities, especially in markets with weak regulations or emerging markets. The aim of this research is to find out whether there are indicators of insider trading from stock split policies based on similar behavior in capital markets where capital market regulations are still not well regulated ( emerging markets ). By using the event study method, this research did not find any indication of insider trading because there was no cumulative abnormal return in the positive direction before the stock split was executed. By using multiple regression analysis, this research confirms that there is no indication of insider trading which is influenced by the level of state ownership, small company asset size and the tendency to split shares with a high split ratio as has been tested by previous research.

Logistic regression in approximation of the results of gas chromatographic analysis of thermally unstable compounds

Regularities and peculiarities of gas chromatographic analysis of thermally unstable compounds were considered on the example of mixture of the reaction products of isopropylbenzene (cumene) free-radical chlorination. The principal constituent in this mixture is (1-chloro-1-methylethyl)benzene, which has the lowest thermal stability, and is partially converted to a-methylstyrene, the only product of its thermal destruction at the chromatograph injector temperatures up to 300 °С. Nevertheless, the results of the study confirms that the gas chromatographic analysis of chloroalkylarenes is possible without their decomposition with the injector temperatures up to 200 °С, even if the analytes contain chlorine atoms at the tertiary carbon atoms and in the “benzylic” positions relative to the aromatic fragment. Similar control of thermal stability of analytes can be recommended for other samples contained potentially unstable constituents. It is shown that thermal decomposition of thermally unstable constituents of samples cannot be revealed from the results of gas chromatographic analysis with capillary columns using variations of their absolute peak areas. Such task can be solved only by using relative peak areas calculated in respect to thermally stable compounds. The dependencies of relative peak areas of unstable constituents vs. temperature (descending), as well as those of their decomposition products (ascending) are characterized by presence of two limits. Low temperature limits correspond to the real content of unstable constituents or their decomposition products is the samples, while the upper limits – to the composition of such samples at their hypothetically complete destruction. Such dependencies can be approximated by logistic regression equation if sampling into capillary columns is carried out at relatively high split ratios (approx. not less than 10 : 1). At lower split ratios the temperature dependencies of peak areas of unstable constituents and products of their transformation are strongly distorted by so-called sample’s composition discrimination effects that make impossible data approximation using logistic regression.

Investigation of OFDM-Based HS-PON Using Front-End LiFiSystem for 5G Networks

Fifth-generation (5G) technology has enabled faster communication speeds, lower latency, a broader range of coverage, and greater capacity. This research aims to introduce a bidirectional high-speed passive optical network (HS-PON) for 5G applications and services including mobile computing, cloud computing, and fiber wireless convergence. Using 16-ary quadrature amplitude modulation orthogonal frequency division multiplexing techniques, the system transmits uplinks and downlinks with a pair of four wavelengths each. Light fidelity (LiFi) services are provided with blue light-emitting-diode-based technology. With a threshold bit error rate (BER) of 10−3, the results demonstrate reliable transportation over a 100 km fiber at −17 dBm received power and in a maximum LiFi range of 20 m. Furthermore, the system offers symmetric 4 × 50 Gbps transmission rates under the impact of fiber–LiFi channel impairments with maximum irradiance and incidence half-angles of 500. Additionally, at threshold BER, the system provides a detection surface range from 1.5 to 4 cm2. Compared to existing networks, the system also provides a high gain and low noise figure. A number of features make this system an attractive option. These include its high speed, high reach, high split ratio, low cost, easy upgradeability, pay-as-you-grow properties, high reliability, and ability to accommodate a large number of users.

An investigation of the cavitation and vibration phenomena in a cylindrical cyclone

Cylindrical cyclones are a popular choice for oil-water separation and sewage treatment in the petroleum industry. Here, we investigate the cavitation and vibration phenomena in a cylindrical cyclone with a vortex finder by using various cyclone operating parameters and conducting multiphase flow numerical simulations. The lowest point of pressure on the cross section of the main cylinder is defined as the pressure center point and is used to understand the generation of the flow field oscillation, which is shown to exhibit an approximately circular motion. This circular oscillation of the flow field is an important characteristic that influences the overall performance and behavior of the cyclone system. Cavitation analysis results show that an increase in the inlet velocity leads to more intense cavitation and an expansion of the cavitation area. At lower split ratios, cavitation primarily occurs at the junction of the inlet pipe and the main cylinder, while at higher split ratios, the cavitation area gradually extends into the overflow pipe. Additionally, structural response analysis demonstrates that increasing the inlet velocity and overflow split ratio significantly enhances the vibrational degree of the structure, leading to greater stress levels. Adjusting the oil content at the inlet has a relatively minimal impact on the structural response compared with the influence of the inlet velocity and split ratio. Furthermore, dimensional analysis is used to analyze the change of wall pressure, and the wall pressure that induces structural vibration can be calculated using the inlet velocity and the split ratio.

Wheel‐based 5G fronthaul/backhaul hybrid MDM‐NGPON/FSO system under Gamma‐Gamma turbulence and weather effects

SummaryThis work presents the bidirectional and symmetric 40 Gbps wheel architecture comprising 16 channels‐based bidirectional hybrid next generation passive optical network with free space optics (NGPON/FSO) system using mode division multiplexing (MDM) scheme. The system incorporates a low‐cost high bandwidth and integrated time and wavelength division multiplexing with orthogonal frequency division multiplexing (TWDM‐OFDM) for data transmission over mixed fiber‐FSO links to various end users at donut modes 0 and 1. This system enhances the fifth generation (5G)‐based networks reliability, survivability, and flexibility, especially in rural places where the core fiber link may be damaged/destroyed under diverse turbulent and weather conditions. The obtained results depict the faithful multimode fiber range of 100 km with fixed FSO range of 100 m at −17 dBm receiver sensitivity and low power penalty of 0.2 dB at 10−9 bit error rate. Maximum FSO range of 2800 m under weak‐to‐strong Gamma‐Gamma turbulence and the effect of fog, rain, snow, and snow with rain can be obtained successfully with fixed 50 km fiber length. Also, the proposed wheel architecture provides superior performance over hybrid ring‐mesh architecture with high split ratio of 1:64. Moreover, the system can sustain up to 70 remote nodes at symmetric 10 Gbps throughput providing high gain, high optical signal‐to‐noise ratio, and low noise figure. The comparative literature work also reveals that the proposed architecture offers high bandwidth, security, long‐reach, and cost‐effectiveness in 5G fronthaul/backhaul networks.

Water interference in the chromatographic analysis of exhaled breath samples: Challenges and mitigation strategies

This study demonstrates the adverse effects of water in exhaled breath samples on the accuracy of breath biomarker analysis when using gas chromatography. The presence of water in exhaled breath significantly modifies the retention times and peak areas of compounds, particularly for low-boiling, early eluting compounds. To tackle this issue, a two-step approach is introduced. The process begins with thorough desorption of the sorbent tube using a high split ratio and a short analysis duration, followed by a secondary analysis of the same tube. The efficacy of the new, straightforward approach was illustrated using humid breath samples and 57 compound standard mixture. This study highlights the importance of proper sample pretreatment and analysis to ensure reliable and accurate results in clinical research.

Assessing the efficiency of CO2 hydrogenation for emission reduction: Simulating ethanol synthesis process as a case study

Hydrogenation of CO2 to synthesize ethanol is a potential way to reduce CO2 emissions while producing value-added fuels and chemicals. However, the emission of tail gas as well as the consumption of heat and electricity may also generate additional CO2 emissions. This raises the question of how efficient this process is in reducing CO2 emissions. In this study, Aspen Plus is used to investigate the efficiency of this process towards reduction of CO2 emission. The effect of key parameters such as single pass CO2 conversion, tail gas splitting ratio, and reaction temperature on CO2 conversion efficiency, hot utility/electricity consumption, as well as CO2 emission reduction/utilization rate is examined. It is recommended that a medium single pass conversion (e.g., 15%), a high splitting ratio (e.g., 0.8), and a relatively high reaction temperature (e.g., 250 ℃) for practical applications of this technology. With an annual CO2 processing capacity of 268 kt, our study suggests that up to 86.9% of CO2 emissions can be eliminated, resulting in the production of 141 kt/year of ethanol, demonstrating the high efficiency of this process in reducing CO2 emissions.

Fabrication and performance evaluation of nonpolarizing beam splitter with high splitting ratio in 780 nm band

Fabrication and performance evaluation of nonpolarizing beam splitter with high splitting ratio in 780 nm band

Novel Data-Aided Carrier Frequency Offset Compensation Methods Using Asymmetric-Shape Constellations for Burst-Mode Coherent Reception

This paper introduces a novel data-aided carrier frequency offset (CFO) estimation and compensation method for m-array phase shift keying (m-PSK) signals in burst-mode digital coherent reception. Its key advances are as follows; the use of newly designed training symbols (TS) that exhibit asymmetric distributed constellations after differential decoding and a vector summation based feed-forward CFO estimation algorithm. These offer short response time and strong robustness to training symbols (TS) timing detection error with wide CFO estimation range of ±B/2, where B is signal baudrate. We evaluate the feasibility of the proposal by simulations of and experiments on 12.5-Gbaud SP-QPSK signals that target optical budget enhancement of 25-Gbps/λ-class PONs to realize long-reach and high splitting ratio optical access. The 100-km burst-mode transmission experiments confirm the proposal offers high sensitivity detection of better than −43 dBm with much wider CFO range of above ±10 GHz.

Subwavelength dichroic demultiplexer based on double Fabry-Perot cavities.

Plasmonic demultiplexers hold promise for the realization of the subwavelength and high-splitting ratio dichroic splitter and have a wide range of applications from optical communication, and manipulation to ultrafast data treatment. However, this vision has not been realized for a long time due to lacking the suitable splitting structure design, which limits its further development of integrated photonic circuits. Here, we demonstrate a plasmonic demultiplexer with subwavelength feature size (0.54 µm) and broadband spectral (620-870 nm) range, and high-splitting ratio (17 dB in experiments and 20 dB in calculations). It consists of two adjacent Fabry-Perot cavities (covered by PMMA polymer) and coupling gratings, which are integrated with the Au waveguide. The relatively simple double cavities design of our device has a simple theoretical analysis and fabrication process. Our work has relevance for various optical applications, such as multiple wavelength photodetectors and optical multichannel interconnects.

Foundry-fabricated grating coupler demultiplexer inverse-designed via fast integral methods

Silicon photonics is an emerging technology which, enabling nanoscale manipulation of light on chips, impacts areas as diverse as communications, computing, and sensing. Wavelength division multiplexing is commonly used to maximize throughput over a single optical channel by modulating multiple data streams on different wavelengths concurrently. Traditionally, wavelength (de)multiplexers are implemented as monolithic devices, separate from the grating coupler, used to couple light into the chip. This paper describes the design and measurement of a grating coupler demultiplexer—a single device which combines both light coupling and demultiplexing capabilities. The device was designed by means of a custom inverse design algorithm which leverages boundary integral Maxwell solvers of extremely rapid convergence as the mesh is refined. To the best of our knowledge, the fabricated device enjoys the lowest insertion loss reported for grating demultiplexers, small size, high splitting ratio, and low coupling-efficiency imbalance between ports, while meeting the fabricability constraints of a standard UV lithography process.

Numerical analysis and artificial neural network-based prediction of two-phase flow pressure drop of refrigerants in T-junction

The two-phase flow behaviors in T-junction are quite complex in energy transport systems. In this paper, the two-phase flow pressure drop of refrigerants in a horizontal branching T-junction was analyzed numerically and predicted using artificial neural network. Firstly, the distribution of static and total pressure was obtained based on Eulerian method, and the parametric studies on the local pressure drop were conducted. It is observed that the vortexes in the entrance of branch pipe lead to the pressure fluctuation and irreversible pressure losses, and the “descend-ascend” of static and total pressure happens under high mass flow split ratio in run pipe. Then, the ANN predicting model of local pressure drop coefficients was established. It shows that GA-BPNN and PSO-BPNN has the best predicting ability for K12J and K13J respectively, and the relative errors are within 10% for most cases. Finally, the sensitivity analysis was conducted, indicating that the effect of mass flow split ratio (F) and inlet quality (x1) is the most significant for K12J and K13J respectively.

Fast Feed-Forward Optical and Electrical Gain Control to Extend the Dynamic Range of the Burst-Mode Digital Coherent Receiver for High-Speed TDM-PON Systems

This paper introduces a new burst-mode coherent receiver configuration that drastically widens the receiver input dynamic range. Its key advance is a fast feed forward gain control scheme for both a semiconductor optical amplifier (SOA) used as a preamplifier and trans-impedance amplifiers (TIAs) set at the coherent receiver. The two-stage optical and electrical gain control greatly decreases the received burst signal's power variations and increases the receiver dynamic range which attenuates the quantization errors in analogue-to-digital conversion (ADC). To elucidate the receiver sensitivity characteristics, bit error rate (BER) calculations are conducted on 10 Gbit/s single polarization quadrature phase shift keying (SP-QPSK) signal coherent reception. The calculations focus on two significant parameters that greatly impact the quantization noise; ADC vertical resolution and received signal's state of polarization (SOP). The calculation results confirm that the proposed configuration achieves high sensitivity, better than −44 dBm, and wide dynamic range of 30 dB in the worst SOP condition, even when 5-bit ADC is used. Transmission experiments verify the calculated sensitivities and extremely high loss budget of 48.6 dB is achieved in 40-km single mode fiber (SMF) transmission. These results show that the proposal has the potential to realize 10 Gbit/s class long-reach and high splitting ratio PONs; the extremely wide dynamic range yields 40 km reach PON systems with 512- or 1024-way splits with no change in receiver configuration.

One-thousandth-level laser power stabilization based on optical feedback from a well-designed high-split-ratio and nonpolarized beam splitter.

Laser power stabilization plays a significant role in atomic and molecular physics, quantum precision measurement, and optical sensing and measurement. In the classical method of using a feedback control loop to stabilize the laser power, the beam splitter is the conjunction element to connect the feedback beam inside the loop and the output beam outside the loop. The stability of its split ratio will directly affect the result of power stabilization, especially in demand of high split ratios for high-efficiency output. For the compatibility of a high split ratio and high stability in a power-stabilized system, we designed and manufactured a high-split-ratio nonpolarized plate beam splitter, whose split ratio was insensitive to variations of beam intensity, polarization, and ambient temperature. Based on the optical feedback of the designed beam splitter, the light intensity was closed-loop controlled by an acousto-optic modulator; finally, the power outside the loop was stabilized as well. The output power was stabilized at 537 mW and a 6 h long-term test was performed. The relative stability of laser power outside the loop in terms of root mean square and peak to peak was 2.72×10-4 and 1.60×10-3, respectively. The relative Allan standard deviation reached 2.78×10-5 at an average time of 200 s. These results will greatly benefit many practical fields that require laser power stabilization with high split ratios and one-thousandth-level stability.

Individual investor attention to stock split and the disposition effect

PurposeThis paper investigates whether individual investors are attentive to stock splits and whether higher split ratios (stronger private information signals) reduce the disposition effect.Design/methodology/approachThis study employs stock split events and transaction data in the Indonesia Stock Exchange (IDX) from January 2004 to December 2017. The authors measure individual investors' attention using buy-initiated trades. To test the effect of split signal on disposition effect, the authors regress individual investors' sell-initiated trades on past stock returns.FindingsUnlike Birru (2015), the authors find that individual investors are attentive to stock splits, especially when stock split ratios are high. In turn, stock splits tend to weaken the disposition effect. The higher the stock split ratios, the weaker the disposition effect.Research limitations/implicationsThis study has a limitation in that the authors exclude all stock splits with dividend events around the split date. These stock splits cover 37% of all splits in Indonesia.Practical implicationsPractically, individual investors should look for stock-related information to reduce disposition bias.Originality/valueTo the best of authors’ knowledge, this study is the first to test individual investors' attention on stock splits based on their buy-initiated trades. This study is also the first to test the impact of stock split ratios on the disposition effect reduction. This study's findings enrich the scant literature on individual investors' attention and how to reduce their disposition effect bias.

Experimental study on the design of light phase outlets for a novel axial oil-water separator

Oil-water separation plays a serious role in oil exploitation to reduce the production cost. Centrifugal separation is one of the feasible methods due to its large capacity, high separation efficiency and low maintenance cost. Besides, the centrifugal separation equipment can be divided into tangential inlet separators and axial inlet separators. The ones with tangential inlet have received a large number of investigation on structure optimization but some shortcomings limit the further improvement of separation performance. In this paper, an axial separator with multiple-stage separation was introduced and investigated experimentally with water flow rate range from 3 to 7 m3/h and inlet oil fraction below 10%. Additionally, the schedule for Light Phase Outlets (LPOs) was studied experimentally and theoretically to ensure high separation efficiency and low split ratio. The results show that the multiple stage separator can keep high separation performance that the oil concentration in HPO is below 200 ppm while the split ratio ranged from 0.2 to 0.45 within experimental conditions. Besides, the reasonable schedule can lead an obvious drop in split ratio with high separation performance. Additionally, based on the analysis of flow field characteristic, the LPOs positioned in the two sides of the oil core can ensure the discharge of oil droplets in high swirl flow field and the LPO located downstream has better potential to separate small size droplets.

Flexible coherent UDWDM-PON with dynamic user allocation based on limited-tunability lasers

Coherent wavelength division multiplexing (WDM) technologies have leveraged the optical communication systems in core networks, increasing the fiber capacity by transmission with advanced modulation formats and mitigation of impairments with digital signal processing. However, these solutions are too expensive for access networks, where cost, power budget, and footprint are limited. Hence, the key technology will be developing low-cost coherent transceivers providing an excellent selectivity and giving high sensitivity, which allows high splitting ratios. This paper reports an experimental design of a low-cost coherent ultra-dense WDM passive optical network (UDWDM-PON) with 6.25 GHz channel spacing. The users’ optical network unit (ONU) is built employing coherent transceivers with two paired low-cost distributed feedback (DFB) lasers, one as the local oscillator and another as the transmitter, offering simplicity and low-cost hardware; likewise, the optical line terminal (OLT) at the central office can profit from the same design. The ONU DFB lasers have wavelengths with limited thermal tunability, controlled by a thermo-electric cooler, which is used to allocate the wavelengths. A medium access control (MAC) at the OLT manages the spectrum channel allocation for ONUs, demanding connection when activation is requested: the OLT furnishes an optical carrier wavelength for the ONU to obtain connection by a control algorithm, assigning a down-channel and another paired up-channel assigned to the ONU DFB transmitter. The MAC can reassign the channels because of interference or collision in a dynamic wavelength allocation. Measures in an activation process and in channel reassignment have been performed in environmental conditions, including control signals and the physical parameters of DFB lasers, demonstrating the practical viability of the PON scaling from 32 up to 256 wavelength channels.

Experimental investigation on phase separation comparison between single and double T-junctions

In this work, experiments were carried out to compare the phase separation performance of double branching T-junction with that of single branching T-junction. The inlet and outlet branches of double T-junction were arranged horizontally with the inner diameter of 8 mm. R134a was used as the working fluid. The inlet mass flow rate (mass flux) was set at 10, 15, 20, 25 g s−1 (199, 298, 398, 497 kg m−2 s−1) and the inlet quality was set at 0.3, 0.5, 0.7 respectively in the experiment of single T-junction. It is concluded that the inlet mass flux has little influence on phase separation while the phase separation efficiency drops sharply with the increase of inlet quality, which is consistent with the conclusions in literature. The experimental data is also compared with the predicted values generated by theoretical models based on air-water and it is found that there is no model suitable for refrigerants. Furthermore, a comparative study between single T-junction and double T-junction was carried out from two perspectives: separation performance comparison of different branches and comparison between single and double T-junctions. The results show that the double T-junction performance is greatly affected by inlet quality and mass split ratio of the first branch, and not always higher than that of single T-junction for horizontal arrangement. Finally, predicting equations of outlet quality of double T-junction are correlated based on experimental data, which have a high predicting accuracy under the high mass split ratio conditions.