scholarly journals Fast Policy Interpretation and Dynamic Conflict Resolution for Blockchain-Based IoT System

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Yaozheng Fang ◽  
Zhaolong Jian ◽  
Zongming Jin ◽  
Xueshuo Xie ◽  
Ye Lu ◽  
...  
Keyword(s):  
Conflict Resolution ◽  
High Speed ◽  
Security Attacks ◽  
Policy Conflict ◽  
Resolution Rate ◽  
Policy Interpretation ◽  
Redundant Data ◽  
Smart Contract ◽  
Resolution Algorithm ◽  
Runtime Information

Although the blockchain-based Internet of Things (BC-IoT) has been applied in many fields, it still faces many security attacks due to lacking policy-based security management (PbSM). Previous PbSM is usually time-consuming, which is difficult to integrate into BC-IoT directly. The high-latency policy conflict resolving in traditional PbSM cannot meet the BC-IoT’s low-latency requirement. Moreover, the conflict resolution rate is low as the PbSM usually neglects the runtime information. Therefore, it is challenging that achieving an efficient PbSM for BC-IoT and overcomes both time and resource consumption. To address the problem, we propose a novel PbSM for BC-IoT named FPICR to realize fast policy interpretation and dynamic conflict resolution efficiently. We first present policy templates based on system log to interpret policy in high speed in BC-IoT. Benefiting from matching the characteristics of the system processing, FPICR supports interpreting a policy into the smart contract directly without complex content parsing. We then propose a weighted directed policy graph (WDPG) to evaluate the importance of the deployed policies more accurately. To improve the policy conflict resolution rate, we implement the resolution algorithm through reconstructing the WDPG. Taking the traits of these properties, FPICR thus can also remove the redundant data to compress storage space by the WDPG. Experiment results highlight that FPICR outperforms the baseline in all measure metrics. Especially, compared with the state-of-the-art method, the speedup of interpretation in FPICR is about up to 2.1 × . The conflict resolution rate in FPICR can be improved by 6.2% on average and achieve up to 96.1%.

Reduction of Emissions From a High Speed Passenger Ferry

2004 ◽  
Author(s):  
Gregory J. Thompson ◽  
Nigel N. Clark ◽  
Mridul Gautam ◽  
Daniel K. Carder ◽  
Sam George
Keyword(s):  
Diesel Fuel ◽  
High Speed ◽  
Water Injection ◽  
Airflow Rate ◽  
Oxides Of Nitrogen ◽  
Redundant Data ◽  
Marine Diesel ◽  
Shaft Torque ◽  
Marine Vessels ◽  
Passenger Ferry

Emissions from marine vessels are being scrutinized as a major contributor to the total particulate matter (TPM), oxides of sulfur (SOx), and oxides of nitrogen (NOx) environmental loading. Fuel sulfur control is the key to SOx reduction but NOx and PM production are primarily engine design dependent. Significant reductions in the emissions from on-road vehicles have been achieved in the last decade and emissions from these vehicles will be reduced by another order of magnitude in the next five years. These improvements have served to emphasize the need to reduce emissions from other mobile sources, including off-road equipment, locomotives, and marine vessels. Diesel-powered vessels of interest include ocean-going vessels with low- and medium-speed engines, as well as smaller vessels with medium- and high-speed engines. A recent study examined to use of intake water injection (WIS) and ultra low sulfur diesel (ULSD) fuel to reduce the emissions from a high-speed passenger ferry in southern California. One of the four Detroit Diesel 12V92 two-stroke, high-speed engines that power the ferry was instrumented to collect intake airflow rate, fuel flow rate, shaft torque, and shaft speed. Engine speed and shaft torque were uniquely linked for given vessel draft and prevailing wind and sea conditions. A raw exhaust gas sampling system was utilized to measure the concentration of NOx, carbon dioxide (CO2), and oxygen (O2), with a mini dilution tunnel sampling a slipstream from the raw exhaust was used to collect TPM on 70 mm filters. The emissions data were processed to yield brake-specific mass results. The emissions measurement system that was employed allowed for redundant data to be collected for quality assurance and quality control. To acquire the data, the ferry was operated at five different steady-state speeds. Three modes were executed in the open sea off Oceanside, CA, idle and harbor modes were also selected for the test matrix. Data have showed that the use of ULSD along with water injection (WIS) could significantly reduce the emissions of NOx and PM while not affecting fuel consumption or engine performance, when compared to baseline marine diesel fuel. The results showed that a normal 40% reduction in TPM was realized when switching from marine diesel fuel to ULSD. A small reduction in NOx was also shown between the marine fuel and the ULSD. The implementation of the WIS reduced NOx by 11% to 17%, depending upon the operating condition. With the WIS, TPM was reduced by a few percentage points, which was close to the confidence level of the measurements.

scholarly journals ICI Cancellation in OFDM Systems by Frequency Offset Reduction

2014 ◽  
Vol 513-517 ◽  
pp. 3987-3991
Author(s):  
Naveed Ur Rehman ◽  
Lei Zhang ◽  
Muhammad Zahid Hammad ◽  
Emmanuel Anania Mwangosi
Keyword(s):  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Video Data ◽  
Modulation Scheme ◽  
Ofdm Systems ◽  
Receiver Side ◽  
High Data ◽  
Redundant Data ◽  
Wide Range

The rapid growth within the field of digital communication during the recent years expanded the need for high-speed data transmission to support a wide range of services such as: video, data and voice in wireless communication systems, etc. Orthogonal frequency division multiplexing (OFDM) and a multicarrier modulation scheme are employed to achieve the high data rates. Since OFDM is very much sensitive to carrier frequency offsets, which cause the Inter-carrier Interference (ICI) leads to mitigation of this ICI is necessary. The objectives of this paper are to, proposed an efficient ICI self-cancellation scheme to mitigate the effect of ICI on OFDM systems. For this purpose, a redundant data is transmitted onto adjacent sub-carriers such that the ICI between adjacent sub-carriers cancels out at the receiver side. One data symbol is modulated into a group of adjacent sub carriers with a group of weighting coefficients. At the receiver side, the received signals are linearly combined on these sub carriers with proposed coefficients. The residual ICI contained in the received signals can then be further reduced. This study provides significant carrier-to-interference power ratio (CIR) improvement, which has been studied theoretically and supported by simulations. Since no channel equalization is required to reduce ICI, so the proposed scheme doesnt increase the system complexity.

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