Channel Flow Control Research Articles

High-Speed Channel Flow Control with Porous Inserts

High-Speed Channel Flow Control with Porous Inserts

Comparing timed-division multiplexing and best-effort networks-on-chip

Best-effort (BE) networks-on-chips (NOCs) are usually preferred over time-division multiplexed (TDM) NOCs in multi-core platforms because they are work-conserving and have lower (zero-load) latency. On the other hand, BE NOCs are significantly more expensive to implement than TDM NOCs because of their virtual channel buffers, allocators/arbiters, and (credit-based) flow control; functionality that a TDM NOC avoids altogether.The objective of this paper is to compare the performance of BE and TDM NOCs, taking hardware cost into consideration. The networks are compared using graphs showing average latency as a function of offered load. For the BE NOCs, we use the BookSim simulator, and for the TDM NOCs, we derive a queuing theory model and an associated TDM NOC simulator.Through experiments with both router architectures, packet length, link width, and different traffic patterns, we show that for the same hardware cost, a TDM NOC can provide higher bandwidth and comparable latency. We also show that the packet length is the most important factor affecting the TDM period, which again is the primary factor affecting latency. The best TDM NOC design for BE traffic uses single flit packets, wide links/flits, and a router with two pipeline stages: link and router traversal.

Study on the channel flow control mechanism of an equidensity particle agent in fractured-vuggy carbonate reservoirs

ABSTRACT To define the channel flow control (CFC) mechanism of the equidensity particle agent, the effect of CFC treatment in fractured-vuggy carbonate reservoirs was systematically analyzed by visual simulation experiments and field tests. The typical visual experimental model of the fractured-vuggy reservoir was designed based on the fractured-vuggy reservoir outcrop characteristics. It overcomes the shortcomings of the conventional model, whose experimental results are greatly affected by subjective factors. The water breakthrough in the dominant flow channel caused substantial shielded remaining oil to be left in the reservoir, resulting in violent flooding of the oil well. The shielded remaining oil accounted for approximately 43.8% of reserves, which is the potential point of the CFC treatment. The CFC treatment can effectively enhance the shielded remaining oil recovery by 22.2% in laboratory experiments. Based on its own efficient suspension and migration ability, the equidensity particle agent can be transferred to the whole dominant flow channel in the fractured-vuggy carbonate reservoirs. By using the multistage distributed shrinkage joint at the outlet of each vuggy and inside of each fracture to control the flow capacity, the equidensity particle agent can equably control the dominant flow channel along the path to realize a wide range of water flooding in the fractured-vuggy carbonate reservoirs.

Performance evaluation of interference aware topology power and flow control channel assignment algorithm

Multi-Radio Multi-Channel Wireless Mesh Network (MRMC-WMN) has been considered as one of the key technology for the enhancement of network performance. It is used in a number of real-time applications such as disaster management system, transportation system and health care system. MRMC-WMN is a multi-hop network and allows simultaneous data transfer by using multiple radio interfaces. All the radio interfaces are typically assigned with different channels to reduce the effect of co-channel interference. In MRMC-WMN, when two nodes transmit at the same channel in the range of each other, generates co-channel interference and degrades the network throughput. Co-channel interference badly affects the capacity of each link that reduces the overall network performance. Thus, the important task of channel assignment algorithm is to reduce the co-channel interference and enhance the network performance. In this paper, the problem of channel assignment has been addressed for MRMC-WMN. We have proposed an Interference Aware, Topology, Power and Flow Control (ITPFC) Channel Assignment algorithm for MRMC-WMN. This algorithm assignes the suitable channels to nodes, which provides better link capacity and reduces the co-channel interference. In the previous work performance of the proposed algorithm has been evaluated for a network of 30 nodes. The aim of this paper is to further evaluate the performance of proposed channel assignment algorithm for 40 and 50 nodes network. The results obtained from these networks show the consistent performance in terms of throughput, delay, packet loss and number of channels used per node as compared to LACA, FCPRA and IATC Channel Assignment algorithms.

Experimental study the effect of turbulent flows in bend channels as to a result of vegetation groin structure on permeable type

Highly dynamic changes in flow regimes are caused by relatively high rainfall intensity, so that the excessive flood volume in the last ten years, and it is caused by watersheds experiencing a crisis or degradation due to conversion into economic and non-economic areas which ultimately impacts on river bank and beds by turbulent flow. The use of groin structure as a method of scouring prevention and channel flow control has not been able to fully meet the expectations of scouring prevention. We obtain the effect of changing the turbulent flow regime on the use of groins on the bent channel. Testing was conducted through laboratory experiments in artificial conditions to investigate the relationship between variables by providing certain treatments in several experimental groups with a comparative control of bend channel angle uses 60° with distance variations of groins and discharge; in addition, software Surfer used to describe scour contour pattern. Analysis of changes in flow behavior is done by using Froude (Fr) and Raynolds (Re) number approaches with the effect of turbulent flow on the bent channel scour. The results of the research indicate that the placement of the groins on the river bank channel bend causes a new phenomenon of turbulent flow with shear stress, resulting in local scouring around groin structure and the placement of looser permeable groin gives prevention 81% of river bank scour.

New channel flow control agent for high-temperature and high-salinity fractured-vuggy carbonate reservoirs

ABSTRACT To improve the oil recovery of high-temperature and high-salinity fractured-vuggy carbonate reservoirs, a new channel flow control (CFC) agent was investigated for the realization of deep water transfer. The density, stability, temperature resistance and physical simulation analysis of the CFC agent were evaluated. The CFC agent was produced using the twin screw extrusion technology at high temperatures with various functional materials. The particle size can be controlled in the range of 0.5 to 2 mm. The density of the CFC agent can be controlled to be equal to that of the injected water, which provides it with good suspension ability. The CFC agent is suitable for fractured-vuggy carbonate reservoirs up to 180 °C. The CFC agent can expand 1–3 times by adjusting the ratio of composition. Multiple particles can stick to one another to form a barrier to plug the dominant flow channel. The injection pressure is 19.2 times as high as that before the CFC treatment. The CFC mechanism is also proposed. The CFC agent can completely satisfy the requirements of dominant channel flow treatments in high-temperature and high-salinity fracture-vuggy carbonate reservoirs.

Study on the channel flow control regulation of particle agents in fractured-vuggy carbonate reservoirs via CFD-DEM coupling method

To define the migration and channel flow control (CFC) law of the particle plugging agent in fractured-vuggy carbonate reservoirs, the motion of the particles in the fractured-vuggy model was numerically analyzed via the computational fluid dynamics-discrete element method (CFD-DEM) coupled method. Typical vug and fracture models were established. The particle flow in the typical models was numerically analyzed. The density of the plugging agent equal to that of injected water is the main controlling factor of deep migration. It is inevitable that particles would remain in the vug which has a negative effect on the CFC treatment in fractured-vuggy carbonate reservoirs. The particle stuck is the key to realize the accumulation of the particle plugging agent. The ratio between the fracture width and the particle diameter is 3.2:1.4–3.0:1.0 when the particles get stuck in the fracture. Most of the particle retention is in the form of free accumulation in the fracture. The decrease in the free flow area caused by particle retention is the main channel flow control mechanism in the fracture.

Separation of particles with bacterial size range using the control of sheath flow ratio in spiral microfluidic channel

A method of concentrating and separating small particles with a specific size in a microfluidic system can be applied to obtain high-purity biological samples, such as viruses, bacteria, and cells. This paper presents the highly efficient separation method of bacteria-sized particles using Dean flow and inertial force in a curved spiral microfluidic channel. By adjusting the flow rate ratio of particle solution to sheath flow at the inlet, the stream line of small particles circulating in the transverse direction with Dean flow becomes more distinct from large particle stream line focused at specific equilibrium position by inertial force. Therefore, submicron-sized particles can be separated from larger particles with high efficiency. In addition, the effects of the number of small particle circulations with Dean flow on the extraction efficiency have been studied. The fluidic channel has been tested for the separation of fluorescent particles with diameters of 0.81 μm, 2.29 μm, and 4.70 μm. The channel design and flow control were optimized so that 0.81-μm particles circulated in the channel along with Dean flow, while 2.29-μm and 4.70-μm particles were concentrated at separate equilibrium points by the inertial force. The extraction yields of 0.81-μm, 2.29-μm, and 4.70-μm particles were measured to be 98.42%, 97.69%, and 99.17%, respectively. Moreover, separation of bacteria from 2.29-μm and 4.70-μm particles has been demonstrated with 98.01% extraction yield.

Interference Aware, Topology, Power and Flow Control Channel Assignment Algorithm for Multi-Radio Multi-Channel Wireless Mesh Networks

Interference Aware, Topology, Power and Flow Control Channel Assignment Algorithm for Multi-Radio Multi-Channel Wireless Mesh Networks

Daily berth planning in a tidal port with channel flow control

This paper studies an operational-level berth allocation and quay crane assignment problem (daily berth planning) considering tides and channel flow control constraints. An integer programming model is proposed for this problem. Then a column generation solution approach is developed on a set partitioning based reformulation of the original model. Computational study is conducted on 30 test cases constructed from real-world data to validate efficiency of the proposed solution approach. Results show that this simple but practical solution approach can optimally solve the daily berthing planning problem instances with up to 80 vessels, 40 berths, and 120 quay cranes within one hour, which is reasonable and acceptable for the real-world applications. The proposed decision model and the solution approach could be potentially useful for some tidal ports with (or without) navigation channels.

A Virtual Channel Allocation Algorithm for NoC

Virtual channel (VC) flow control proves to be an alternative way to promote network performance, but uniform VC allocation in the network may be at the cost of chip area and power consumption. We propose a novel VC number allocation algorithm customizing the VCs in network based on the characteristic of the target application. Given the characteristic of target application and total VC number budget, the block probability for each port of nodes in the network can be obtained with an analytical model. Then VCs are added to the port with the highest block probability one by one. The simulation results indicate that the proposed algorithm reduces buffer consumption by 14.58%–51.04% under diverse traffic patterns and VC depth, while keeping similar network performance.

Packet Switched Network on Chip (NOC) using Round Robin Arbiter Based AES Encryption and Decryption Algorithm

Network-on-Chip (NOC) has developed as a new method to integrate large number of cores on a single silicon die. Processing elements are interconnected through packet-based network in NOC architecture. The NOC architecture consists of physical layer, the data link layer and the network layer of OSI protocol stack. In this paper, NOC router based packet switching network with Round Robin Arbiter has been proposed. In packet switching method, Data's are transmitted in short packets. Packets are received, stored briefly and forward to the next node. All packets are routed through the shortest paths and maintaining the performance of Noc in the presence of faults. The packet switching network with virtual channel flow control provides the flexibility, area and energy efficiency. NOC provides essential advantages such as scalability, increased parallelism of partial dynamic configuration. The main focus of this work is to reduce the frequent checking of unconnected nodes and making the return path delay. Finally, the packet switched NOC using Round Robin arbiter is incorporated into AES Encryption and Decryption algorithm, which is used to protect the information. In this proposed design, is to reduce the power, delay and area and also improves the performance of the architecture. NoC data transport medium, which is commonly occupied by FIFO buffers and routing logic. The proposed packet switched network on chip using round robin algorithm based AES encryption and decryption has been simulated by using Model Sim 6.3c and synthesized by Xilinx 12.4I design tool.

BiLink: A high performance NoC router architecture using bi-directional link with double data rate

This paper presents a novel high performance Network-on-Chip (NoC) router architecture design using a bi-directional link with double data rate (BiLink). Ideally, it can provide as high as 2 times speed-up compared with the conventional NoC router. BiLink utilizes an extra link stage between routers and transmits two flits in one link per cycle using phase pipelining if both routers require to use the current link. To further increase the effective bandwidth, the direction of each link can be configured in every clock cycle to cater for different traffic loads from each side. Therefore, the data rate can be as high as 4 times compared with conventional NoC routers under uneven traffic. Centralized mode control scheme is implemented using a finite state machine (FSM) approach. Cycle-accurate simulations are carried out on both synthetic traffic patterns as well as real application benchmarks. Simulation results show that BiLink can provide as high as 90% and 250% speedup compared with conventional NoC routers for even and uneven traffic, respectively. 2X and 3X gains in throughput are obtained under even and uneven traffic, respectively, when compared with the conventional NoC router for the virtual channel flow control. The BiLink router architecture is synthesized using TSMC 65nm process technology and it is shown that an area overhead of 28% over state-of-the-art bi-directional NoC is introduced while the critical path is about 9% higher than that of the conventional routers. Despite the overhead in critical path and power consumption, a 47.45% improvement of Energy-Delay-Product (EDP) is achieved by BiLink under high injection rate traffic.

Flow Control Channel behind a Backward-Facing Step in a Duct

Flow control over a backward-facing step (BFS) by continuous suction/blowing is numerically investigated. This study examines the influence of blowing/suction rate, and slot size on the detachment process. Fluid flow is assumed turbulent, incompressible, 2D and steady in average. The governing equations are discretised by the finite volume method based on the k-ε RNG one point closure turbulence model. The investigations were performed for a Reynolds number of 3.5 104 with respect to the step height (h). Several blowing/suction rates are checked (-0.035 < Cq < +0.035) for four slot size cases namely (a = 0.95 mm, 2.25 mm, 3 mm and 5 mm). All results indicate that suction/blowing shortens the reattachment length and reduces the turbulence energy. The detailed flow structure suggests a way of shortening of the recirculation length with increasing the blowing/suction rate. Through different flow conditions, two correlations for reattachment length related to blowing or suction rate are proposed. The smallest slot size produces greatest turbulence kinetic energy and maximum friction all considered suction/blowing rates.

Control mechanism of turbulent channel flow by spatially spanwise oscillating Lorentz force

Turbulent channel flow control by using a spanwise oscillating Lorentz force with steady distributions has been investigated numerically via the pseudo-spectral method. The turbulent control and the drag reduction can be achieved by spanwise oscillating Lorentz forces with proper control parameters. The vortex generation is impacted in the controlled turbulent channel flow, and that only periodically well-organized streamwise vortexes are observed in the near-wall region of the turbulent channel flow. If the turbulent control is regarded as a process in which the turbulence flow is modulated by the induced flow, it has been shown that the induced flow dominants the modulated flow field when the turbulent flow is effectively controlled by the Lorentz force. Therefore, basic features of streamwise vortices in the controlled flow, such as configurations, distributions and its formations and annihilations, are related with the induced flow field and the Lorentz force distributions closely, based on which the mechanism of the turbulent control is elucidated finally.

Increasing Interconnection Network Throughput with Virtual Channels

Interconnection networks form the backbone of scalable computer systems, including high-performance computers and datacenters. High-performance networks must provide high throughput and bandwidth while delivering messages with minimal latency. As processors that connect to the network inject more messages, the network load rises and can cause two potential deleterious conditions: network deadlock—where messages are blocked in the network and cannot progress—and an exponential increase in end-to-end latency, as messages must wait in the network for prior messages to be delivered. The network architect’s job is to deliver high bandwidth and low latency for the largest network load possible, but with limited cost and power. Before the 1990s, scalable computing systems were typically built with two separate networks to avoid deadlock. These networks were often assigned to “request” and “reply” traffic classes, and messages in separate classes did not interfere as they progressed through the network. The networks had their own individual wires to ensure that reply messages did not get stuck behind request messages. Unfortunately, this approach increases network cost by doubling the number of wires, and can leave links idle as congestion rises. In “Virtual Channel Flow Control” (IEEE Trans. Parallel and Distributed Systems, vol. 3, no. 2, 1992, pp. 194–205), William J. Dally proposed an alternate approach to alleviate deadlock and provide better network performance. Virtual channels include two or more virtualized networks that share the physical wire links and routers, but have their own buffer storage for in-flight messages. In modern interconnection networks, messages are decomposed into flow-control digits (flits) that transit the network like train cars. When a message reaches a congested point, its flits reside in the virtual channel buffers, leaving the links free for messages belonging to other virtual channels. The decoupling of buffering from links in virtual channels enables deadlock-free routing algorithms and the passing of blocked messages in the network, using otherwise idle link resources. With virtual channels, a system doesn’t incur the link cost of multiple networks and can more easily multiplex traffic from different flows over a single set of physical links.

Improvement of shallow subway tunnel ventilation procedures

The article describes the full-scale tests on temperature in tunnel lining and adjacent soil in shallow subways operating in the extreme continental climate conditions. The mathematical modeling of air flow in the subway tunnel ventilation is presented. The authors have worked out recommendations on architectural concept of escapes from a subway platform. The system offered for air flow control in a ventilation branch consists of a platform fan delivery control channel and a tunnel air flow control channel.

3P1-B06 バイオレジストを用いた超精密オンチップ流体制御(バイオアセンブラ(2))

We present an innovative on-chip flow control system. Proposed on-chip control system consists of cell delivery channel and flow control channel. Flow control channel is connected in parallel to cell delivery channel. Flow control in a cell delivery channel is achieved by changing flow resistance in flow control channel. Changing of flow resistance is achieved by using gel actuator made of Bioresist. Bioresist is thermo responsible biocompatible photoresist. Novelties of this on-chip flow control system are shown as follows. (1) It is possible to actuate under 1V. (2) It is easy to integrate other cell measurement devices. Here, we fabricated and demonstrated this system and achieved on-chip flow control.

Spatial simulation of channel flow instability and control

AbstractA direct numerical simulation is performed on the full time-dependent three-dimensional Navier–Stokes equations in a spatially developing plane-channel flow at a Reynolds number of 10 000. Two-dimensional eigenfunctions based on the solution of the Orr–Sommerfeld equation are introduced at the inflow with random noise added to simulate a vibrating ribbon transition experiment. The flow is allowed to choose a natural path to secondary instability, either K-type (after Klebanoff) or H-type (after Herbert), depending on the amplitude of the two-dimensional disturbance. For low-amplitude two-dimensional disturbances (1 % of the centreline velocity), H-type modes are found to dominate, while a doubling of the amplitude (2 % of the centreline velocity) produces a mixed H-type/K-type disturbance field with explosive growth of the secondary modes. In addition, the use of a suction/blowing slot that is phase lagged with respect to a fixed wall pressure signal is demonstrated to significantly reduce the energy in the primary mode owing to the destruction of phase between the streamwise and wall-normal velocity components. The use of forward finite-time Lyapunov exponents to generate Lagrangian coherent structures as a means of flow visualization is also presented, showing qualitative agreement with previous experimental visualizations, and represents a viable means of identifying characteristic vortical flow structures.

A Cross-Layer QoS-Aware Communication Framework in Cognitive Radio Sensor Networks for Smart Grid Applications

Electromagnetic interference, equipment noise, multi-path effects and obstructions in harsh smart grid environments make the quality-of-service (QoS) communication a challenging task for WSN-based smart grid applications. To address these challenges, a cognitive communication based cross-layer framework has been proposed. The proposed framework exploits the emerging cognitive radio technology to mitigate the noisy and congested spectrum bands, yielding reliable and high capacity links for wireless communication in smart grids. To meet the QoS requirements of diverse smart grid applications, it differentiates the traffic flows into different priority classes according to their QoS needs and maintains three dimensional service queues attributing delay, bandwidth and reliability of data. The problem is formulated as a Lyapunov drift optimization with the objective of maximizing the weighted service of the traffic flows belonging to different classes. A suboptimal distributed control algorithm (DCA) is presented to efficiently support QoS through channel control, flow control, scheduling and routing decisions. In particular, the contributions of this paper are three folds; employing dynamic spectrum access to mitigate with the channel impairments, defining multi-attribute priority classes and designing a distributed control algorithm for data delivery that maximizes the network utility under QoS constraints. Performance evaluations in ns-2 reveal that the proposed framework achieves required QoS communication in smart grid.