SMER:a secure method of exchanging resources in heterogeneous internet of things

The number of IoT(internet of things)connected devices increases rapidly.These devices have different operation systems and therefore cannot communicate with each other.As a result,the data they collected is limited within their own platform.Besides,IoT devices have very constrained resources like weak MCU(micro control unit)and limited storage.Therefore,they need direct communication method to cooperate with each other,or with the help of nearby devices with rich resources.In this paper,we propose a secure method to exchange resources(SMER)between heterogeneous IoT devices.In order to exchange resources among devices,SMER adopts a compensable mechanism for resource exchange and a series of security mechanisms to ensure the security of resource exchanges.Besides,SMER uses a smart contract based scheme to supervise resource exchange,which guarantees the safety and benefits of IoT devices.We also introduce a prototype system and make a comprehensive discussion.

All-and mixed-dielectric grating for Nd:glass-based high-energy pulse compression

Maximizing the energy-loading performance of gratings is a universal theme in high-energy pulse compression.However,sporadic grating designs strongly restrict the development of high-power laser engineering.This study proposes an all-and mixed-dielectric grating design paradigm for Nd:glass-based pulse compressors.The solution regions are classified according to the line density.High diffraction efficiency solutions are described in more detail based on the dispersion amount and incident angle.Moreover,an energy scaling factor of 7.09 times larger than that of the National Ignition Facility’s Advanced Radiographic Capability(NIF-ARC)is obtained by taking advantage of the low electric field intensity at transverse magnetic polarization and a small incident angle.These results make a pioneering contribution to facilitate future 20–50-petawatt-class ultrafast laser systems.

Posture-invariant hybrid scaling weight measurement algorithm for live eels

To obtain higher economic benefits,large eel breeding companies classify live eels by weight.Due to their strong mobility and smooth body surface,living eels are not suitable for traditional mechanical weight measurement.In this study,a live eel sorting machine based on machine vision was developed,and a novel method was developed for obtaining live eel weight measurements through images.First,a backlit workbench was designed to capture static images of eels,and then the projection area and skeleton length of the images were obtained by image preprocessing.For the eel's body shape,which is generally cylindrical and gradually transitions to a flat tail,the tail posture changes affect the shape of the images;thus,a weight measurement model combining the projected area and the skeleton length was proposed.The optimal scale division coefficient of the weight model was found to be 0.745 by experimentation.Then,select eels of different weight ranges were used for model error verification and to obtain the correction function of the error.The weight gradient was used to confirm the corrected eel weight model.Finally,the system calculation results were compared with the actual measurement results.The root mean square error(RMSE)was 12.94 g,and the mean absolute percentage error(MAPE)was 2.12%.The results show that the proposed method provided a convenient,fast,and low-cost non-contact weight measurement method for live eels,reduced the damage rate of live eels,and can meet the technical requirements of actual production.

Achieving high throughput and TCP Reno fairness in delay-based TCP over large networks

The transport control protocol （TCP） has been widely used in wired and wireless Intemet applications such as FTP, email and HTTP. Numerous congestion avoidance algorithms have been proposed to improve the performance of TCP in various scenarios, especially for high speed and wireless networks. Although different algorithms may achieve different performance improvements under different network conditions, designing a congestion algorithm that can perform well across a wide spectrum of network conditions remains a great challenge. Delay-based TCP has a potential to overcome above challenges. However, the unfairness problem of delay-based TCP with TCP Reno blocks widely the deployment of delay-based TCP over wide area networks. In this paper, we proposed a novel delay-based congestion control algorithm, named FAST-FIT, which could perform gracefully in both ultra high speed networks and wide area networks, as well as keep graceful faimess with widely deployed TCP Reno hosts. FAST-FIT uses queuing delay as a primary input for controlling TCP congestion window. Packet loss is used as a secondary signal to adaptively adjust parameters of primary control process. Theoretical analysis and experimental results show that the performance of the algorithm is significantly improved as compared to other state-of-the-art algorithms, while maintaining good faimess.

TCP-ACC： performance and analysis of an active congestion control algorithm for heterogeneous networks

Transmission control protocol （TCP） is a reli- able transport layer protocol widely used in the Internet over decades. However, the performances of existing TCP conges- tion control algorithms degrade severely in modern heteroge- neous networks with random packet losses, packet reordering and congestion. In this paper, we propose a novel TCP algo- rithm named TCP-ACC to handle all three challenges men- tioned above. It integrates 1） a real-time reorder metric for calculating the probabilities of unnecessary Fast Retransmit （FRetran） and Timeouts （TO）, 2） an improved RTT estima- tion algorithm giving more weights to packets that are sent （as opposed to received） more recently, and 3） an improved congestion control mechanism based on packet loss and re- order rate measurements. Theoretical analysis demonstrates the equilibrium throughput of TCP-ACC is much higher than traditional TCP, while maintaining good fairness with regard to other TCP algorithms in ideal network conditions. Ex- tensive experimental results using both network emulators and real network show that the algorithm achieves signifi- cant throughput improvement in heterogeneous networks as compared with other state-of-the-art algorithms.