改进的多输人多输出正交频分复用水声通信判决反馈信道估计算法

针对最小均方误差准则下(Minimum Mean Square Error,MMSE)判决反馈信道估计算法在多输入多输出正交频分复用(Multiple-input Multiple-output Orthogonal Frequency Division Multiplexing,MIMO-OFDM)低信噪比水声通信环境下存在误码遗传缺陷,提出了一种基于压缩感知理论的改进的MMSE判决反馈信道估计算法。通过结合浅海水声信道的稀疏性特点,利用编码校验后的信息与原始信息实现了对信道估计的判决反馈更新,采用匹配追踪算法改进MMSE判决反馈追踪信道估计技术,实现了抑制传统判决反馈信道估计算法在迭代更新及传递过程中存在的误码遗传的目的。仿真和水池实验结果证实:改进的MMSE判决反馈追踪信道估计算法不仅可以有效的抑制误码遗传,对抗突发噪声,跟踪信道的缓慢时变,同时大幅降低了导频占用率,提高了通信质量。

Frequency Diversity for OFDM Mobile Communication via Underwater Acoustic Channels

The major constraint on the performance of orthogonal frequency division multiplexing （OFDM） based underwater acoustic （UWA） communication is to keep subcarriers orthogonal. In this paper, Doppler estimation and the respective compensation technique along with various diversity techniques were deliberated for OFDM-based systems best suited for underwater wireless information exchange. In practice, for mobile communication, adjustment and tuning of transducers in order to get spatial diversity is extremely difficult. Considering the relatively low coherence bandwidth in UWA, the frequency diversity design with the Doppler compensation function was elaborated here. The outfield experiments of mobile underwater acoustic communication （UWAC） based on OFDM were carried out with 0.17 bit/（s-Hz） spectral efficiency. The validity and the dependability of the scheme were also analyzed.

Neuromuscular electrical stimulation and testosterone did not influence heterotopic ossification size after spinal cord injury: A case series

Neuromuscular electrical stimulation(NMES) and testosterone replacement therapy(TRT) are effective rehabilitation strategies to attenuate muscle atrophy and evoke hypertrophy in persons with spinal cord injury(SCI). However both interventions might increase heterotopic ossification(HO) size in SCI patients. We present the results of two men with chronic traumatic motor complete SCI who also had pre-existing HO and participated in a study investigating the effects of TRT or TRT plus NMES resistance training(RT) on body composition. The 49-year-old male, Subject A, has unilateral HO in his right thigh. The 31-year-old male, Subject B, has bilateral HO in both thighs. Both participants wore transdermal testosterone patches(4-6 mg/d) daily for 16 wk. Subject A also underwent progressive NMES-RT twice weekly for 16 wk. Magnetic resonance imaging scans were acquired prior to and post intervention. Cross-sectional areas(CSA) of thewhole thigh and knee extensor skeletal muscles, femoral bone, and HO were measured. In Subject A(NMES-RT + TRT), the whole thigh skeletal muscle CSA increased by 10%, the knee extensor CSA increased by 17%, and the HO + femoral bone CSA did not change. In Subject B(TRT), the whole thigh skeletal muscle CSA increased by 13% in the right thigh and 6% in the left thigh. The knee extensor CSA increased by 7% in the right thigh and did not change in the left thigh. The femoral bone and HO CSAs in both thighs did not change. Both the TRT and NMES-RT + TRT protocols evoked muscle hypertrophy without stimulating the growth of preexisting HO.

MRI analysis and clinical significance of lower extremity muscle cross-sectional area after spinal cord injury

Shortly after spinal cord injury（SCI）, the musculoskeletal system undergoes detrimental changes in size and composition, predominantly below the level of injury. The loss of muscle size and strength, along with increased immobility, predisposes persons with SCI to rapid and severe loss in bone mineral density and other health related consequences. Previous studies have highlighted the significance of measuring thigh muscle cross-sectional area, however, measuring the size and composition of muscles of the lower leg may provide insights on how to decrease the risk of various comorbidities. The purpose of the current review was to summarize the methodological approach to manually trace and measure the muscles of the lower leg in individuals with SCI, using magnetic resonance imaging. We also intend to highlight the significance of analyzing lower leg muscle cross-sectional area and its relationship to musculoskeletal and vascular systems in persons with SCI.

Association Rule Analysis-Based Identification of Influential Users in the Social Media

The exchange of information is an innate and natural process that assist in content dispersal.Social networking sites emerge to enrich their users by providing the facility for sharing information and social interaction.The extensive adoption of social networking sites also resulted in user content generation.There are diverse research areas explored by the researchers to investigate the influence of social media on users and confirmed that social media sites have a significant impact on markets,politics and social life.Facebook is extensively used platform to share information,thoughts and opinions through posts and comments.The identification of influential users on the social web has grown as hot research field because of vast applications in diverse areas for instance political campaigns marketing,e-commerce,commercial and,etc.Prior research studies either uses linguistic content or graph-based representation of social network for the detection of influential users.In this article,we incorporate association rule mining algorithms to identify the top influential users through frequent patterns.The association rules have been computed using the standard evaluation measures such as support,confidence,lift,and conviction.To verify the results,we also involve conventional metrics for example accuracy,precision,recall and F1-measure according to the association rules perspective.The detailed experiments are carried out using the benchmark College-Msg dataset extracted by Facebook.The obtained results validate the quality and visibility of the proposed approach.The outcome of propose model verify that the association rule mining is able to generate rules to identify the temporal influential users on Facebook who are consistent on regular basis.The preparation of rule set help to create knowledge-based systems which are efficient and widely used in recent era for decision making to solve real-world problems.

Assessing the potential landslide risk identification in the northern section of CPEC route Pakistan based on Multi-Temporal InSAR approaches

Landslides are the most frequent geoenvironmental natural hazards in hilly regions,owing to broken rock masses and slope instability.Every year,landslides occur along the Karakorum highway in the northern section of the China-Pakistan Economic Corridor,involving complex geological action and causing significant damages and fatalities.To mitigate landslide hazard risks and a better understanding of landslide occurrence in steep mountainous regions,a comprehensive and precise analysis of slow-moving landslides is necessary.To address this challenge,a Multi-Temporal(MT),Interferometry Synthetic Aperture Radar(InSAR)approach using Small Baseline Subsets and Interferometric Point Target Analysis techniques was utilized to extract ground deformation rates.A total of 121 multitrack synthetic aperture radar images from Sentinel-1A were acquired from 2021 to 2023,enabling the detection and monitoring of ground displacement over time.Eight active slope movements were successfully identified by calculating the differences in deformation,indicating a significant deformation rate within the trust fault lines and regional geological formations.The research findings reveal that the regional geological structure,including lithology and fault lines,significantly increase the deformation rate.These identified landslide hazard areas range from 1.47 km2 to 14.88 km2,with an annual average rate of line of sight surface displacement estimated between−4.13 to−16.07 cm/yr.The MT-InSAR analysis demonstrates that fault lines and geology play significant role in surface deformation,providing valuable insights into the deformation induced by regional tectonic activities.

Exhumation History and Exploration Potential of Gold Deposits in the NE Jiaodong Peninsula,North China:Evidence from Apatite and Zircon Fission Track Thermochronology

As the most important gold producer in China,the Northwest Jiaodong Peninsula is famous for its large gold deposits.In recent years,the discovery of gold mineralization has reached a depth of 4000 m below the surface in this region.It has attracted significant interest from explorers about the prospecting potential at greater depths.Besides,the current deep drilling shows that the prospecting effect in the west portion is better than the region to the east.Does it imply that there is a difference in prospecting potential between the east and the west?This paper seeks to address the issue through fission track thermochronology on apatite and zircon to reveal the temperature-time evolution relationship of rock mass and to inverts their thermal evolution history.In addition,this study analyzes the transformation of ore deposits after mineralization,quantitatively calculates the uplift-erosion rate of rock mass,and summarizes the preservation law of ore deposits.Based on the thermal history simulation of the apatite fission track,our results show that the Guocheng gold belt has experienced three stages of thermal evolution:108-74,74-27,and 27-0 Ma.The uplift and cooling processes of the threestage tectonic uplift events are the results of multi-stage Pacific plate accretion.The calculated total denudation depth of the gold deposit in the Guocheng gold belt from Cretaceous to the present is about 3.4-5.3 km.The metallogenic depth of the ore body in the gold belt is 5.6-8.0 km,which indicates that the ore body in the Guocheng gold belt has suffered a significant degree of denudation.It is speculated that the location with less denudation in the southwest has greater prospecting potential.Our results quantitatively identify the uplift and denudation of the deposit after mineralization,which provides a new theoretical reference for regional mineralization,deep prospecting and exploration.