Spectral Data For L^2 Cohomology

We study the spectral data for the higher direct images of a parabolic Higgs bundle along a map between a surface and a curve with both vertical and horizontal parabolic divisors. We describe the cohomology of a parabolic Higgs bundle on a curve in terms of its spectral data. We also calculate the integral kernel that reproduces the spectral data for the higher direct images of a parabolic Higgs bundle on the surface. This research is inspired by and extends the works of Simpson [21] and Donagi-Pantev-Simpson [7]

HST-MRF: Heterogeneous Swin Transformer with Multi-Receptive Field for Medical Image Segmentation

The Transformer has been successfully used in medical image segmentation due to its excellent long-range modeling capabilities. However, patch segmentation is necessary when building a Transformer class model. This process may disrupt the tissue structure in medical images, resulting in the loss of relevant information. In this study, we proposed a Heterogeneous Swin Transformer with Multi-Receptive Field (HST-MRF) model based on U-shaped networks for medical image segmentation. The main purpose is to solve the problem of loss of structural information caused by patch segmentation using transformer by fusing patch information under different receptive fields. The heterogeneous Swin Transformer (HST) is the core module, which achieves the interaction of multi-receptive field patch information through heterogeneous attention and passes it to the next stage for progressive learning. We also designed a two-stage fusion module, multimodal bilinear pooling (MBP), to assist HST in further fusing multi-receptive field information and combining low-level and high-level semantic information for accurate localization of lesion regions. In addition, we developed adaptive patch embedding (APE) and soft channel attention (SCA) modules to retain more valuable information when acquiring patch embedding and filtering channel features, respectively, thereby improving model segmentation quality. We evaluated HST-MRF on multiple datasets for polyp and skin lesion segmentation tasks. Experimental results show that our proposed method outperforms state-of-the-art models and can achieve superior performance. Furthermore, we verified the effectiveness of each module and the benefits of multi-receptive field segmentation in reducing the loss of structural information through ablation experiments

Frost Growth Detection Using Capacitive Sensor

Frost buildup on surfaces could be an undesired situation in many applications. In refrigeration and heat pump system, typically, frost grows on the fin surface of the heat exchanger due to different environmental/operational conditions. On one hand, it can block the air flow and increase air-side pressure drop; on the other hand, can increase the thermal resistance and deteriorate heat transfer performance. As a result, frost buildup can significantly reduce the system’s COP. Therefore, most systems encountered frost buildup run the defrost cycle. The frost growth process is affected by many factors, such as environmental conditions (air humidity, temperature, flow rate), operational conditions (working fluids, saturated temperature), heat exchangers (structures, fin type and fin surface wettability) et. al.. All those factors are coupled together, which makes frost growth a very complex dynamic process with variable spatial distribution of its characteristic parameters. It is very important to dynamically detect frost growth for both effective defrost control and precise frost modelling. In this work, a capacitive sensor for frost detection has been developed, which consists of three parts as shown in Figure 1(a): 1) commercial capacitive to digital converter (FDC2214 from Texas Instruments and the resolution of the reading is 0.0001pF), 2) PCB connector and 3) fabricated electrodes. The fabricated copper electrode is attached to the PCB connector, which is mounted to the capacitive to digital converter and connected to the computer by a USB interface. Capacitance variation can be measured when the target properties changes. The interdigital electrodes has a high sensitivity and were fabricated by lithophotography, using copper laminates/ deposited copper thin layer as shown in Figure 1(b) The sensitivity can be affected by metallization ratios, width and thickness of the insulation layer, which are also explored in this work. The frost grows on a cold plate which is placed in the wind tunnel with a controlled air temperature, humidity and flow rate. The electrode of the capacitive sensor is located beside the side wall of the cold plate, as shown in Figure 1(c). The frost growth process can be detected and reflected by the capacitance variation of the sensor, as shown in Figure 2, the capacitance variation can reflect different stage of the frost growth period, starting from condensation to mature growth. Images are also captured by a CCD camera to calibrate the signal. This work demonstrates the dynamic frost growth detection at the first time and could play a significant role to understanding frost growth mechanism and defrost control strategy

Moving P2P Live Streaming to Mobile and Ubiquitous Environment

Media streams distribution over a wired network to static hosts can be realized by Client/Server mode or Peer-to-Peer overlay networks. However, if the end hosts are mobile over heterogeneous wireless access networks, one needs to consider many operational issues such as network detection, handoff, join and leave latency, and desired level of quality of service, as well as caching. In the latest researches, one popular P2P live streaming system, called AnySee, over the wired network, has been deployed and widely used. Based on the AnySee system, this paper proposed and implemented one hybrid live streaming system, AnySee-Mobile, under wired and wireless environment. In the system, one wireless peer will be selected to act as an agent. One agent has two main functions, to request media from P2P overlay network as a normal peer, and to multicast media to WLAN as a multicast source. In this paper we study, how to elect one multicast agent in WLAN. Several experimentations have been made and proved that the system has good user experiences and performances

Deduplication-based Energy Effcient Storage System in Cloud Environment

In cloud computing, companies usually use high-end storage systems to guarantee the I/O performance of virtual machines (VM). These storage systems cost a lot of energy for their high performance. In this paper, we propose an EEVS, a deduplication-based energy efficiency storage system for VM storage. We firstly investigate some VM image files with general operating systems. With the analysis result, we find there are many redundant data blocks that bring extra energy cost VM storage. Therefore, in the EEVS, we design an online-deduplication mechanism to reduce these redundant data without service interruption, while traditional deduplication technology is used for offline backup. Based on the system design, we implement an EEVS with the existing cloud platform. Since this mechanism needs considerable computing resources, we design a deduplication selection algorithm such that the storage energy consumption is minimized for a given set of VMs with limited resources for deduplication. Experiment results in a para-virtualization environments of the EEVS show that energy consumption is reduced by even up to 66% with negligible performance degradation

Experimental Study of Condensation Heat Transfer of R134a on Oil-infusion Surfaces

Dropwise condensation, since first recognized in 1930, has stimulated interest because its heat transfer coefficient (HTC) is much higher than film condensation. For some applications, not only a higher heat transfer performance is desired, but also the retention of the fluids on the surface can be a big issue. For example, the refrigerant retention in some enhanced tube can block the contact of the vapor-solid interface and increase the thermal resistance; it also can increase the charge of refrigerant because certain amount of refrigerant could not go through the system cycle. Many efforts were dedicated to modifying the surface and promote dropwise condensation, and most research focus on the condensation of water vapor. It is very challenging to promote dropwise condensation for working fluids with a lower surface tension than water, such as refrigerant. Research have been conducted on dropwise condensation for low surface tension fluids using oil-infusion surface, which is promoted by the contact of drop to the liquid-vapor interface instead of solid-vapor interface. However, the effectiveness and efficiency of the oil-infusion surface is still a critical challenge, and the heat transfer mechanism of dropwise condensation with such liquid-liquid interface stays unclear. In this work, condensation of R134a on oil-immerged surfaces is investigated. Heat transfer coefficient is measured, and formation of the condensate is observed using a high speed camera. Two cavity surfaces of different porous scale are examined, of which, one is nanoscale pores and another is microscale pores Mineral oil of low miscibility to R134a is soaked to be saturated in the cavity prior to the experiment. All experiments were conducted under saturated condition of ambient temperature (around 22 °C) in a pressure chamber. The subcool level of the condensation is 10 °C. Images of the local condensation formation is analyzed and heat transfer coefficient is also compared for different surfaces. The duration of the oil-infusion surface is also tested for both surfaces

Constructing magnetic Si-C-Fe hybrid microspheres for room temperature nitroarenes reduction

This research is supported by the National Natural Science Foundation of China (21174112). X.W. acknowledges support from School of Engineering, the University of Aberdeen. The useful discussion with Dr. M.D. Symes (University of Glasgow) is gratefully acknowledged.Peer reviewedPostprin

On Performance Debugging of Unnecessary Lock Contentions on Multicore Processors: A Replay-based Approach

Locks have been widely used as an effective synchronization mechanism among processes and threads. However, we observe that a large number of false inter-thread dependencies (i.e., unnecessary lock contentions) exist during the program execution on multicore processors, thereby incurring significant performance overhead. This paper presents a performance debugging framework, PERFPLAY, to facilitate a comprehensive and in-depth understanding of the performance impact of unnecessary lock contentions. The core technique of our debugging framework is trace replay. Specifically, PERFPLAY records the program execution trace, on the basis of which the unnecessary lock contentions can be identified through trace analysis. We then propose a novel technique of trace transformation to transform these identified unnecessary lock contentions in the original trace into the correct pattern as a new trace free of unnecessary lock contentions. Through replaying both traces, PERFPLAY can quantify the performance impact of unnecessary lock contentions. To demonstrate the effectiveness of our debugging framework, we study five real-world programs and PARSEC benchmarks. Our experimental results demonstrate the significant performance overhead of unnecessary lock contentions, and the effectiveness of PERFPLAY in identifying the performance critical unnecessary lock contentions in real applications.Comment: 18 pages, 19 figures, 3 table