Short Flow Research Articles

Towards fine-grained load balancing with dynamical flowlet timeout in datacenter networks

In modern datacenter networks (DCNs), load balancing mechanisms are widely deployed to enhance link utilization and alleviate congestion. Recently, a large number of load balancing algorithms have been proposed to spread traffic among the multiple parallel paths. The existing solutions make rerouting decisions for all flows once they experience congestion on a path. They are unable to distinguish between the flows that really need to be rerouted and the flows that potentially have negative effects due to rerouting, resulting in frequently ineffective rerouting. Fine-grained rerouting will also cause severe packet reordering, especially in asymmetric topology scenarios. To address the above issues, we present a fine-grained traffic-differentiated load balancing (TDLB) mechanism, which aims to distinguish flows that are necessarily to be rerouted and reroute traffic in fine-grained without packet reodering. Specifically, TDLB distinguishes the traffic that must be rerouted through the host pair information in the packet header, and selects an optimal path for rerouting. To prevent severe packet reodering caused by excessive path delay differences, TDLB dynamically adjusts the flowlet timeout to segment the traffic and select the optimal path for rerouting. The NS-2 simulation results show that TDLB effectively reduces tail latency and average flow completion time (FCT) for short flows by up to 49% and 46%, respectively, compared to the state-of-the-art load balancing schemes.

High-efficiency microplastic removal in water treatment based on short flow control of hydrocyclone: Mechanism and performance

Microplastics have been identified as a potentially emerging threat to water environment and human health. Therefore, there is a pressing demand for effective strategies to remove microplastics from water. Hydrocyclone offers a rapid separation and low energy consumption alternative but require reduction of microparticle entrainment by short flow, which limits the effectiveness for small density differentials and ultralow concentrations separation. We proposed an enhanced mini-hydrocyclone with overflow microchannels (0.72 mm width) based on the active control of short flow in hydrocyclone for microplastic removal from water. The overflow microchannels effectively redirect the particles that would typically be entrained by the short flow, leading to higher separation efficiency. Simulation results show overflow microchannels effectively reduced short flow to 0.7 %, a reduction of up to 94 % compared to conventional hydrocyclones. The hydrocyclone with overflow microchannel demonstrated a removal efficiency exceeding 98 % for 8 μm plastic microbeads at ultralow concentrations (10 ppm), which is a 33.7 % improvement over conventional hydrocyclone. Compared with other methods (e.g., filtration, adsorption, coagulation) for microplastic removal, this work achieves rapid separation capability and long period operation, highlighting hydrocyclone as a promising approach for microplastic removal in industry-scale water treatment.

Inactivation of Highly Pathogenic Avian Influenza Virus with High-temperature Short Time Continuous Flow Pasteurization and Virus Detection in Bulk Milk Tanks

Infections of dairy cattle with clade 2.3.4.4b H5N1 highly pathogenic avian influenza virus (HPAIV) were reported in March 2024 in the U.S. and viable virus was detected at high levels in raw milk from infected cows. This study aimed to determine the potential quantities of infectious HPAIV in raw milk in affected states where herds were confirmed positive by USDA for HPAIV (and therefore were not representative of the entire population), and to confirm that the commonly used continuous flow pasteurization using the FDA approved 72 °C (161°F) for 15 s conditions for high−temperature short time (HTST) processing, will inactivate the virus. Double-blinded raw milk samples from bulk storage tanks from farms (n = 275) were collected in four affected states. Samples were screened for influenza A using quantitative real-time RT-PCR (qrRT-PCR) of which 158 (57.5%) were positive and were subsequently quantified in embryonating chicken eggs. Thirty-nine qrRT-PCR positive samples (24.8%) were positive for infectious virus with a median titer of 3.5 log10 50% egg infectious doses (EID50) per mL. To closely simulate commercial milk pasteurization processing systems, a pilot-scale continuous flow pasteurizer was used to evaluate HPAIV inactivation in artificially contaminated raw milk using the most common legal conditions in the US: 72 °C (161°F) for 15 s. Among all replicates at two flow rates (n = 5 at 0.5 L/min; n = 4 at 1 L/min), no viable virus was detected. A mean reduction of ≥5.8 ± 0.2 log10 EID50/mL occurred during the heating phase where the milk is brought to 72.5 °C before the holding tube. Estimates from heat-transfer analysis support that standard U.S. continuous flow HTST pasteurization parameters will inactivate >12 log10 EID50/mL of HPAIV, which is ∼9 log10 EID50/mL greater than the median quantity of infectious virus detected in raw milk from bulk storage tank samples. These findings demonstrate that the US milk supply is safe when pasteurized.

Unveiling intricate foam behaviors and dynamic instabilities in a two-phase natural circulation loop with seawater

The use of seawater as an alternative emergency coolant in a nuclear power plant presents great potential to enhance the nuclear safety. The present study investigates the dynamic instabilities during the startup experiments of a natural circulation loop with seawater through synchronization of two-phase flow visualization and measurements of transient fluid flow parameters. The results reveal that in seawater the pressure drop oscillations (PDO) with nature of low-frequency pulse-type loop flow occurs at the modified heat flux of 531.56–654.80 kW/m2. On the other hand, the density wave oscillations (DWO) characterized by high-frequency oscillatory flow prevails at higher modified heat flux of 654.80–1844.46 kW/m2. For the loop with seawater, the flow patterns in the riser may evolve from dispersed bubbly flow, foam flow, foam and short slug flow due to the flashing effects, and foam and long slug flow periodically. The image analysis reveals that the foam fraction may decline from 75% to 52.2%, while the flow pattern transforms from the stage II (foam and cape bubbly flow) to III (foam and long slug flow). On the other hand, the flow pattern may evolve from bubbly flow, cap bubbly flow, turbulent slug flow, and long slug flow in de-ionized water. For DWO, the oscillatory frequency is found to be inlet temperature dependent. Interestingly, both fluids demonstrate identical frequencies of 0.06 Hz, 0.14 Hz, and 0.09 Hz, respectively, corresponding to the inlet temperature range of 40–52 °C, 52–65 °C, and 65–75 °C, despite significantly different evolution of two-phase flow patterns. Indeed, the density wave travels at the same speed through the loop operating at the same power for both seawater and de-ionized water, as the buoyancy force is the primary driving force for the present study. These findings contribute significantly to the better understanding of related industrial processes using seawater as the working fluid.

The relationship between exercise atmosphere, flow experience, and subjective well-being in middle school students: A cross-sectional study.

The aim of this research was to explore the effect of exercise atmosphere (EA) on the flow experience (FE) and subjective well-being (SWB) of middle school students and further analyze the mediating effect of FE between EA and SWB, and to provide theoretical references for improving middle school students' SWB. A cross-sectional design was used. 1056 middle school students from 6 middle schools in Sichuan, China, voluntarily completed the Exercise Atmosphere Scale (EAS), Short (9-item) Dispositional Flow Scales (SDFS-2), Positive and Negative Affect Scale (PANAS), and Satisfaction with Life Scale (SLS). The data collected for this investigation were processed using SPSS 19.0 and Process 3.0. EA could positively predict FE and SWB. FE could positively predict SWB. FE partially mediated the relationship between EA and SWB. The study demonstrated the mediating effect of FE between EA and middle school students' SWB. It was proposed that the positive EA contributes to the emergence of FE during physical exercise in middle school students, which leads to a better sense of SWB.

Combined demographic, ecological and genetic tools reveal connectivity within a fragmented butterfly population

Protected species require targeted studies to establish population sizes, their dispersal capacity and the possible genetic bottleneck effect that could impair the future of the remaining populations. In this study, we used the genotyping-by-sequencing technique (SNP: single nucleotide polymorphism) combined with Capture-Mark-Recapture (CMR) method to measure the dispersal ability and subpopulation sizes of the protected butterfly Zerynthia polyxena in 14 sites of NW Italian Alps. The study species form a metapopulation divided into several small subpopulations (ranging from 90 to 859 estimated subpopulation sizes). The species showed low mobility, likely due to habitat fragmentation, with individuals travelling an average of 80 m from their original capture site. SNPs highlighted high observed heterozygosity, low genetic substructuring at short distances, and large genetic differentiation only for individuals found in sites located at 46 km distance, suggesting high gene flow at short distances and limited gene flow between distant populations. Although CMR data did not detect movement beyond 700 m, the genetic results revealed remarkable connectivity among nearby subpopulations. The results indicate that gene flow still exists among the subpopulations despite the fragmented habitat. Considering that the species is locally threatened by habitat loss due to the planning of a European high-speed railway, our data suggest that it is not too late to adopt conservation measures. In conclusion, combining genetic and ecological studies can be utilised to design proper conservation plans for protected and threatened insect metapopulations.

Study on Short Video Infomercial Avoidance Factors Based on the Perspective of Flow - Taking Tiktok App as an Example

Short video has become a national application at the same time, short video information flow advertising avoidance also continues to appear. Few studies have looked at the avoidance behavior of short video information streams from the perspective of psychological theory and social theory. Taking Tiktok APP as an example and combining the characteristics of short video information stream advertising, this study constructed a model of influencing factors of information stream advertising avoidance from the perspective of flow. In this paper, 220 samples were analyzed by questionnaire survey, and it was found that the scene adaptation of Tiktok information flow advertisements negatively affected the cognitive avoidance and emotional avoidance behaviors of advertisements through the flow state. The push accuracy of Tiktok Yin information flow advertisement negatively affects the cognitive avoidance, emotional avoidance and behavioral avoidance of advertisement through the flow state. The study of advertising avoidance behavior from the perspective of flow has enriched the theoretical perspective of the study of advertising avoidance in short video information flow, and also provided theoretical and practical suggestions for advertisers in short video advertising.

Deconvolution-based correction of pre-strike arc voltage measurement in medium voltage switches

Abstract Switching arc characterization, e.g. measuring the arc voltage and current, is crucial for assessing the performance of power switchgears under different working conditions. This is especially challenging for short circuit current making as one of the most severe operations for medium voltage load break switches. By closing the switch, a short circuit current flows through the arc which is ignited by the electrical breakdown in the gap between contacts before the contacts touch. This results in an abrupt change from the rated voltage of the power network, i.e. tens of thousands of volts, to the switching arc voltage, i.e. a few tens of volts and ultimately zero when the contacts touch. The inherent response of the measurement system to this very large step preceding the arc formation overlaps with the switching arc voltage and results in unrealistic arc voltages which makes correction of the distorted voltage waveform necessary. In this paper, a post processing method based on deconvolution correction technique, i.e. deconvolution of the measured voltage in time and frequency domains, is examined using experimentally determined impulse responses of the measurement system. To demonstrate its effectiveness, this method is applied to three different measurement system configurations with various step responses. The results show practically identical deconvoluted (corrected) voltage waveforms in all three measurement systems, although the directly measured waveforms have significant differences. The corrected arc voltage waveforms are in agreement with the indirect measurements proposed in previous studies.

Selective recovery of vanadium from chloride titanium dioxide effluent and preparation of high-purity thermotropic vanadium dioxide(M): An ammonia-free process

Vanadium recovery is critical for the hazard-free treatment and resourceful utilization of chloride titanium dioxide effluent (CTDE). Traditional ammonia precipitation vanadium recovery process from chloride titanium dioxide effluent suffered issues of the long process, high cost, and severe ammonia pollution risk. To solve these issues, an ammonia-free method consisting of V extraction from chloride titanium dioxide effluent by D2EHPA, direct VO2+ hydrolysis precipitation, and vacuum calcination was designed to produce VO2(M). The effect of conditions on V recovery, impurities behaviors, and vacuum dehydration mechanisms in each step was systematically investigated. Experimental results demonstrated that over 96.50% of vanadium was precipitated in the form of VO2∙xH2O by mixing CaO powder at 25 °C for 5 min until pH reached 4.20. And then, high purity VO2(M) (VO2 >99.50%) was prepared by vacuum calcined at 500 °C for 2 h in the tube furnace. Further characterizations revealed that the crystal structure of the calcined product was a monoclinic crystal structure with the space group of P21/c (VO2(M)), and the phase transition temperature was 57.8 °C. This demonstrated that the produced VO2(M) had met the established market standards and exhibited stable thermotropic degeneration, making it suitable for use in thermistors and other related fields. Compared with the conventional ammonia precipitation V recovery process, the proposed process exhibits a promising industrial application due to the short flow, near-zero wastes, higher economic efficiency, and superior product performance. In conclusion, it provides a clean and efficient vanadium recovery strategy from chloride titanium dioxide effluent.

Physical and Numerical Study on Right Side and Front Side Gas Blowing at Walls in a Single‐Strand Tundish

The compromise between inclusions removal by small bubbles and proper agitation of fluid flow in tundish by gas blown is challenging. The single‐strand tundish without flow control devices (bare tundish) is used to study the effects of side‐wall gas blowing on the flow field. The water model, particle image velocity measurement and computational fluid dynamics simulation are used to study bubble behavior, fluid flow field, and tracer transport. A large horse shoe vortex and a short circuit flow at the bottom are formed in the bare tundish. Gas blowing at the outlet‐side wall of the tundish creates multiple vortices in the right‐side region, with blowing rate and position greatly influencing the surface flow within the tundish. Gas blowing at the front‐side wall creates a large spiral vortex, agitating the fluid in the tundish and improving the flow field. Increasing the blowing rate strengthens the vortex in the right region, but raising the blowing position affects surface flow and creates a counterclockwise flow toward the shroud. In all schemes, gas blowing at a low position on the front‐side wall with a small gas flowrate is the optimized scheme which shows the smallest dead volume and enhances surface flow.

Recovery of rare earth elements from rare earth molten salt electrolytic slag via fluorine fixation by MgCl2 roasting

Rare earth fluoride molten-salt electrolytic slag (REFES) is a precious rare earth element (REE) secondary resource, and considerable amounts of REEs exist in REFES as REF3; they are difficult to dissolve in acid or water and impede efficient REE extraction. In REFES recovery, the REF3 species in REFES are usually transformed into acid-soluble rare earth compounds by NaOH roasting or sulfating roasting and then extracted by acid leaching. Moreover, the fluorides in REFES are released as HF gas in the roasting process or enter the liquid phase during the water washing process; both of these processes cause fluorine pollution. Fixing the fluorine into the solid slag provides a way to avoid fluorine pollution. In this study, a novel method was proposed to extract REEs from REFES via MgCl2 roasting followed by HCl leaching. Thermodynamics calculations and thermogravimetry‒differential thermal analyses (TG-DTA) were conducted to investigate the reactions occurring in the roasting process. First, MgCl2 reacts with the REF3 and RE2O3 to form RECl3 and REOCl, respectively. Second, the RECl3 absorbs water and forms RE(OH)3. Third, MgCl2·6H2O is gradually dehydrated to MgCl2·2H2O and reacts with REF3 and RE(OH)3, and REOCl, MgF2 and MgO are formed. Through HCl leaching, the REOCl in the roasting products is leached by HCl acid, while fluoride remains in the solid slag as MgF2. The optimum experimental conditions are as follows: mass ratio of MgCl2 to REFES of 30%, roasting temperature of 700 °C, roasting time of 2 h, hydrochloride acid concentration of 4 mol/L, leaching time of 2 h, leaching temperature of 90 °C and leaching L/S ratio of 20:1. The efficiencies for total leaching of the REEs, La, Ce, Pr, and Nd are 99.13%, 99.20%, 98.42%, 99.38%, and 99.08%, respectively. Moreover, the concentration of fluoride in the leaching solution is 2.191 × 10−6 mol/L. This method has a short process flow with low reagent costs, and the problem of fluoride pollution from REFES recovery is solved; thus, our study has great industrial application potential.

Effect of uneven inflow on hydrodynamic performance of bulb turbine

Abstract Bulb turbine unit is characterized by its low head, large discharge, and short flow passage. The guiding wall separating the power house section from the flood discharge section may cause uneven inflow before its neighbor units when the power house section is located off the river’s mainstream. In this study, selecting a bulb turbine hydropower station in China as the subject, we establish a three-dimensional CFD model that contains the full flow passage of the turbine unit and partial upstream reservoir, to analyze the effects of uneven inflow on the hydrodynamic performance of the bulb turbine. The results show that under this power station layout, flow separation occurs on the left side of the guiding wall, resulting in a low pressure zone and causing the flow in a three-dimensional vortical pattern. The low pressure and flow energy loss lead to the reduction of the neighbor units’ head, causing the discharge decreasing, and the output cannot reach the expectations. This situation can be improved by shortening the guiding wall, indicating that the unit’s performance is strongly related to the hydraulic structure arrangement. The results can provide some references for the design and operation of the related project.

The dominance and growth of shallow groundwater resources in continuous permafrost environments

Water is a limited resource in Arctic watersheds with continuous permafrost because freezing conditions in winter and the impermeability of permafrost limit storage and connectivity between surface water and deep groundwater. However, groundwater can still be an important source of surface water in such settings, feeding springs and large aufeis fields that are abundant in cold regions and generating runoff when precipitation is rare. Whether groundwater is sourced from suprapermafrost taliks or deeper regional aquifers will impact water availability as the Arctic continues to warm and thaw. Previous research is ambiguous about the role of deep groundwater, leading to uncertainty regarding Arctic water availability and changing water resources. We analyzed chemistry and residence times of spring, stream, and river waters in the continuous permafrost zone of Alaska, spanning the mountains to the coastal plain. Water chemistry and age tracers show that surface waters are predominately sourced from recent precipitation and have short (<50 y) subsurface residence times. Remote sensing indicates trends in the areal extent of aufeis over the last 37 y, and correlations between aufeis extent and previous year summer temperature. Together, these data indicate that surface waters in continuous permafrost regions may be impacted by short flow paths and shallow suprapermafrost aquifers that are highly sensitive to climatic and hydrologic change over annual timescales. Despite the lack of connection to regional aquifers, continued warming and permafrost thaw may promote deepening of the shallow subsurface aquifers and creation of shallow taliks, providing some resilience to Arctic freshwater ecosystems.

Selective preparation of lithium carbonate from overhaul slag by high temperature sulfuric acid roasting – Water leaching

An efficient recycling process is developed to recover valuable materials from overhaul slag and reduce its harm to the ecological environment. The high temperature sulfuric acid roasting - water leaching technology is innovatively proposed to prepare Li2CO3 from overhaul slag. Under roasting conditions, fluorine volatilizes into the flue gas with HF, lithium is transformed into NaLi(SO4), aluminum is firstly transformed into NaAl(SO4)2, and then decomposed into Al2O3, so as to selective extraction of lithium. Under the optimal roasting – leaching conditions, the leaching rate of lithium and aluminum are 95.6% and 0.9%, respectively. Then the processes of impurity removal, and settling lithium are carried out. The Li2CO3 with recovery rate of 72.6% and purity of 98.6% could be obtained under the best settling lithium conditions. Compared with the traditional process, this work has short flow, high controllability, remarkable technical, economic, and environmental benefits. This comprehensive recycling technology is suitable for overhaul slag, and has great practical application potential for the disposal of other hazardous wastes in electrolytic aluminum industry.

Experimental study on gas separation from the oil–water-emulsion mixture via hydrate method

The gas separation technology based on hydrate method offers several advantages, including a short process flow, simple equipment, no pollution, less corrosion, and lower energy consumption. It has a broad application prospect in the acid gas purification, biogas purification and CO2 sequestration., etc. However, demanding hydrate formation conditions and lower gas separation effects constrain its application. Oil-water emulsion shows promise in improving mass and heat transfer efficiency, enhancing hydrate slurry fluidity, and reducing hydrate aggregates. Thus, this study investigates the effects of different oil–water ratios, promoter concentrations, and surfactants on hydrate formation and separation efficiency in an oil–water emulsion system. At an oil–water ratio of 1:1, the purification rate increased to 6.06, five times higher than in a pure water system. The addition of 1,3-Dioxolane (DIOX) facilitated bidirectional growth properties of hydrate formation on droplet surfaces, enhancing hydrate nucleation and formation, leading to a CO2 recovery increase to 87% with 1.5 wt% DIOX. Furthermore, lipophilic surfactants were more likely to promote hydrate slurry fluidization. The addition of Span80 reduced hydrate agglomeration and increased the rate of hydrate formation as concentration rose. The results suggest that adding DIOX and increasing the concentration of Span80 could improve the hydrate method’s separation efficiency at an oil–water ratio of 1:1.

Additive Manufacturing of Rare Earth Permanent Magnetic Materials: Research Status and Prospects

With the rapid development of intelligent manufacturing, modern components are accelerating toward being light weight, miniaturized, and complex, which provides a broad space for the application of rare earth permanent magnet materials. As an emerging near-net-shape manufacturing process, additive manufacturing (AM) has a short process flow and significantly reduces material loss and energy consumption, which brings new possibilities and impetus to the development of rare earth permanent magnetic materials. Here, the applications of AM technology in the field of rare earth permanent magnets in recent years are reviewed and prospected, including laser powder bed fusion (LPBF), fused deposition modeling (FDM), and binder jetting (BJ) techniques. Research has found that the magnetic properties of AM Nd-Fe-B magnets can reach or even exceed the traditional bonded magnets. In addition, in situ magnetic field alignment, in situ grain boundary infiltration, and post-processing methods are effective in enhancing the magnetic properties of AM magnets. These results have laid a good foundation for the development of AM rare earth permanent magnets.

Design of short Venturi flow meters for incompressible and isothermal flow applications

The Venturi flow meter offers a range of measurement options for liquids, gas, steam, and slurries in piped systems. The main criteria for assessing Venturi performance include permanent pressure loss, discharge coefficient, relative pressure loss coefficient, and measurement accuracy. However, the extended length of Venturis, relative to other flow rate measuring instruments, can present limitations in some applications. Furthermore, the manufacturing of shorter Venturis requires less material and energy. This study addresses the challenge by developing shorter Venturi meters that adhere to established performance standards. Previous studies show that cone angles, the ratio of throat diameter to inlet diameter (β-ratio), and the throat length impact the performance of a Venturi. The scope of this research considers single-phase, incompressible and isothermal flows. The investigation focuses on the effect of cone angles for flows with Reynolds numbers ranging from 5000 to 10,000,000. Two axisymmetric Venturis, with a β-ratio of 0.7, were designed and evaluated against an ISO-5167 classical Venturi with the same β-ratio. Despite the ISO-5167 Venturi outperforming the others across the key criteria, a Venturi designed with a 40-degree convergent cone angle and a 10-degree divergent cone angle was 24.9 % shorter than the classical design and demonstrated similar performance to the ISO-5167 Venturi across Reynolds numbers from 100,000 to 10,000,000.

Instant queue occupancy used for automatic traffic scheduling in data center networks

Datacenter applications desire low latency for short messages to provide a better user experience. Therefore, one of the goals of datacenter networks is to minimize flow completion time (FCT), especially for short flows. Multiple scheduling disciplines have been proposed to achieve this goal. In this paper, we develop a Dynamic Longer Stay Less Priority (D-LSLP) which looks at the current queue occupancy to adjust the demotion threshold for the packets of the flows arriving in the strict priority queues. Initially, D-LSLP considers every flow to be a short flow, and with the passage of time, the flow is demoted to the lower priority queue, similar to Multilevel Feedback Queue (MLFQ) Scheduling. It enables short flows to be completed in a couple of higher-priority queues. In contrast, large flows are demoted to the lower priority queues after remaining active in the queues for a certain amount of time (demotion threshold). However, for the different traffic patterns with different distribution of flow lengths, the demotion threshold for the flows should be adapted automatically. In this paper, we leverage the programmable nature of the P4 switches to measure the instant queue occupancy in the P4, which can be used to adjust the demotion threshold accordingly for the highest priority queue. This enables D-LSLP to increase or decrease its highest priority demotion threshold based on the instant queue status. D-LSLP allows multiple traffic patterns to coexist without manually tuning the demotion thresholds. Furthermore, it reduces the tail drop in the highest priority queue when many short flows overwhelm the highest priority queue. The performance evaluation shows that it works equally well for different traffic patterns without operator intervention.

Decentralized Scheduling for Data-Parallel Tasks in the Cloud

For latency-sensitive data processing applications in the cloud, concurrent data-parallel tasks need to be scheduled and processed quickly. A data-parallel task usually consists of a set of sub-tasks, generating a set of flows that are collectively referred to as coflows . The state-of-the-art schedulers collect coflow information in the cloud to optimize coflow-level performance. However, most of the coflows, classified as small coflows because they consist of only short flows, have been largely overlooked. This paper presents OptaX , a decentralized network scheduling service that collaboratively schedules data-parallel tasks’ small coflows. OptaX adopts a cross-layer, COTS (commercial off-the-shelf) switch-compatible design that leverages the sendbuffer information in the kernel to adaptively optimize flow scheduling in the network. Specifically, OptaX (i) monitors the system calls (syscalls) in the hosts to obtain their sendbuffer footprints, and (ii) recognizes small coflows and assigns high priorities to their flows. OptaX transfers these flows in a FIFO manner by adjusting TCP’s two attributes: window size and round-trip time. We have implemented OptaX as a Linux kernel module. The evaluation shows that OptaX is at least 2.2 × faster than fair sharing and 1.2 × faster than only assigning small coflows with the highest priority. We further apply OptaX to improve the small I/O performance of Ursa , a distributed block storage system that provides virtual disks where small I/O is dominant. URSA with OptaX achieves significant improvement compared to the original URSA for small I/O latency.

Hydraulic characterization and start-up of a novel circulating flow bio-carriers

High-quality biofilm carriers are crucial for the formation of biofilm, but problems such as slow biofilm growth on the carrier surface have been troubling a large number of researchers. The addition of a carrier changes the flow state in the reactor, which in turn affects the microbial attachment and the quantity of microorganisms. Also, aerobic microorganisms need to use dissolved oxygen in the water to remove water pollutants. In this paper, a novel recirculating flow carrier with a hollow cylinder structure is proposed, with a certain number of hollow inverted circular plates placed at equal distances inside. In this paper, the hydraulic residence time, aeration volume, and the spacing of the inflow plates of the recirculating flow biofilm carrier, which are three important factors affecting the hydraulic characteristics of the reactor, are first investigated. At the same time, it was compared with the common combined carrier to find the optimal operating conditions for the hydraulic characteristics. Secondly, a reactor start-up study was carried out to confirm that the new recirculating flow biofilm carrier could accelerate the biofilm growth by changing the hydraulic characteristics. The results showed that under the same conditions, the hydraulic properties of the reactor were better with the addition of the recirculating flow carrier, with an effective volume ratio of 98% and a significant reduction in short flows and dead zones. The stabilized removal of COD, NH3-N, and TN in the reactor with the addition of the recirculating flow carrier reached about 94%, 99%, and 91% respectively, at the beginning of the 15th day, which effectively proved the feasibility of the recirculating flow carrier.