Arrays of gold split rings with a 50-nm minimum feature size and with an LC resonance at 200 THz frequency (1.5 microm wavelength) are fabricated. For normal-incidence conditions, they exhibit a pronounced fundamental magnetic mode, arising from a coupling via the electric component of the incident light. For oblique incidence, a coupling via the magnetic component is demonstrated as well. Moreover, we identify a novel higher-order magnetic resonance at around 370 THz (800 nm wavelength) that evolves out of the Mie resonance for oblique incidence. Comparison with theory delivers good agreement and also shows that the structures allow for a negative magnetic permeability.
The X-ray imaging systems dedicated for X-ray spectroscopy, based on a semiconductor strip sensors have been recently an important research topic. The most important research objective is working towards improvement of the spectroscopic and position resolution features [1]–[3]. In spectroscopic applications the short strip silicon detectors are widely used due to their relatively small capacitance and leakage current. Using strip pitch below 75 μm enables achievement of high spatial resolution. In this work, the analysis and design of the read-out electronics for the short silicon strip detectors are presented. The Charge Sensitive Amplifier (CSA) is optimized for the detector capacitance of about 1.5 pF, and the shaping amplifier default peaking time is about 1 μs (controlled by the sets of switches). To achieve the lowest possible noise level, the sources of noise in a radiation imaging system both internal (related to the frontend electronics itself), as well as external, were considered [4]. We target the noise level below 40 el. rms, considering low power consumption (a few mW) and limited channel area. To increase the speed of incoming hits processing, the continuoustime resistive CSA feedback together with a digital feedback reset are included. The prototype integrated circuit comprises of 8 charge processing channels, biasing circuits, reset and base-line restoration logic, and a calibration circuit.
Issues of limited scene adaptability, inadequate evidence preservation, and low efficiency in traditional digital forensics were addressed by analyzing the feasibility of incorporating decentralized, tamper-resistant blockchain technology into digital forensic practices. Initially, a phased forensic process was proposed based on a hierarchical architecture for blockchain forensic technology, examining the advancements of blockchain at each stage of evidence acquisition, preservation, and presentation. Subsequently, limitations in existing research were analyzed, and a digital forensic framework incorporating comprehensive blockchain involvement was designed by utilizing the distributed advantages of blockchain. This framework integrated evidence information into the on-chain data structure and introduced a complementary graph analysis algorithm to standardize evidence collection across various scenarios. An off-chain distributed database was employed to achieve scalable, efficient storage, while smart contract templates enhance the reusability of contracts for similar forensic transactions. Lastly, potential future directions for the application of blockchain technology in forensic science were explored.
To reduce the coding computational complexity of the rate and distortion calculations in HEVC, a fast TU level rate model with higher accuracy was proposed.The contribution percentages of different syntax elements in entropy coding were evaluated, and syntax element-wise accurate rate models were individually developed to construct the whole TU level model.In addition, coefficient levels were weighted adaptively to distinguish the nonuniform contributions of different coefficients in terms of rate profiling.Moreover, position-wise parameter was defined to depict the distribution patterns for possible non-zero coefficients within one block.The final linear rate model was developed by fine-tuning the model parameters from great amounts of samples in a statistical way.Finally, the transform domain distortion model was also established to bypass unnecessary reconstruction process.Experimental results show that the proposed algorithm can achieve 49.76% complexity reduction with 1.74% BD-BR increase for RA configuration.
Shaikh Shakeela, N. Sai Shankar, P Mohan Reddy
et al.
Cyber-attacks are increasing day by day. The generation of data by the population of the world is immensely escalated. The advancements in technology, are intern leading to more chances of vulnerabilities to individual’s personal data. Across the world it became a very big challenge to bring down the threats to data security. These threats are not only targeting the user data and also destroying the whole network infrastructure in the local or global level, the attacks could be hardware or software. Central objective of this paper is to design an intrusion detection system using ensemble learning specifically Decision Trees with distinctive feature selection univariate ANOVA-F test. Decision Trees has been the most popular among ensemble learning methods and it also outperforms among the other classification algorithm in various aspects. With the essence of different feature selection techniques, the performance found to be increased more, and the detection outcome will be less prone to false classification. Analysis of Variance (ANOVA) with F-statistics computations could be a reasonable criterion to choose distinctives features in the given network traffic data. The mentioned technique is applied and tested on NSL KDD network dataset. Various performance measures like accuracy, precision, F-score and Cross Validation curve have drawn to justify the ability of the method.
Кількість радіоелектронних пристроїв постійно збільшується. Це призводить до жорстких вимог щодо захищеності від шумів та чутливості нових пристроїв зв’язку. Нині існує широкий спектр методів, які використовуються для реалізації пристроїв зв'язку з високим рівнем завадостійкості на основі алгоритмів ефективної демодуляції та декодування. Однією з основних частин процесу прийому цифрового сигналу є визначення того, який саме сигнал поступає на вхід приймача. Цей процес зводиться до сканування частот і відповідно до детектування параметрів сигналів та є важливою складовою систем цифрового радіозв’язку. Детектування сигналу забезпечує подальшу правильну обробку та інтерпретацію прийнятої інформації. В статті розглянуті сигнали, які передаються згідно стандарту DVB-S2 і його розширеної ревізії DVB-S2X. Обидві версії стандарту мають майже однакову структуру на фізичному рівні. Подібність сигналів фізичного рівня призводить, наприклад, до того, що при невірному налаштуванні частоти, приймачем DVB-S2 може прийматися сигнал стандарту DVB-S2X. В такому випадку неможливо забезпечити правильну обробку переданої інформації. Розробка ефективного методу виявлення ревізії та декодування службової інформації фізичного рівня DVB-S2/S2X стандарту вирішує дану проблему і розширює можливості проектування нової цифрової електроніки та систем зв'язку з високою стійкістю до шумів. В даній роботі представлено детектор, який дозволяє визначити до якої ревізії належить переданий сигнал та визначити параметри фрейму. Детектор складається із систем кадрової синхронізації, демодулятора та декодера поля PLSCODE. Запропоновано формули розрахунку біт поля PLSCODE і декодування службової інформації відповідно для стандартів широкосмугового оповіщення DVB-S2 та DVB-S2X. Розроблено програмну модель описаного методу. Виконано експериментальні розрахунки ROC кривої та ймовірності пропуску від співвідношення сигнал/шум. Отримані результати моделювання показують ефективність запропонованого методу детектування навіть при негативних співвідношеннях сигнал/шум.
The original discovery of active submarine landslides and turbidity currents in the deep ocean was made in the 1950s through analysis of breaks in transoceanic communications cables. Further insights regarding the causes, frequency, and behavior of damaging submarine flows are presented here, based on recent disruptions of modern communications cables in the Strait of Luzon off southern Taiwan. In 2006, the Pingtung earthquake triggered landslides and at least three sediment density flows (a general term covering turbidity currents and similar flows). These flows sped down submarine canyons and into the Manila Trench at 12.7–5.6 m s–1 (45–20 km h–1), resulting in 22 cable breaks. In 2009, the cables were again damaged, this time by extreme river discharge associated with Typhoon Morakot. Two cables were damaged during the main flood when debris-charged river waters dived to the seabed and down Gaoping Canyon. A second, more damaging sediment density flow formed three days later when river levels were near normal and seismic activity was low. It is suggested that this second flow resulted from deposited flood sediment that was remobilized possibly by internal wave activity. Further breaks were reported in 2010 and 2012. While historical cable break databases are incomplete, they imply that since at least 1989, density flows capable of breaking cables have been infrequent, but they increased markedly after the 2006 Pingtung earthquake—a time that coincided with a transition to more extreme rainfall associated with northward migration of typhoon tracks to Taiwan.
According to the features of short-to-medium reach optical fiber communication systems,three high performance adaptive modulation and coding schemes were investigated.In the first one,a new dimension,forward error correction (FEC),was introduced to the traditional bit and power loading (BPL) scheme,and the three-dimensional adaptive modulation and coding were achieved.The modulation format and FEC code were allocated based on look-up table (LUT).The proposed algorithm has lower complexity and higher data rate compared to the BPL scheme.The second one was also based on LUT method where one similar data rate with the BPL scheme was achieved using partitioned precoding,but peak-to-average power ratio was reduced up to two dB,and the power efficiency was improved.In the last scheme,probabilistic shaping QAM was adopted as the modulation format,and shaping gain and almost indefinitely fine modulation granularity were achieved at the expense of certain complexity.With adaptive partitioned precoding,without decreasing data rate the number of PS-QAM was limited to reduce the complexity.The experimental results demonstrate that the proposed scheme outperforms the BPL scheme in terms of data rate and receiver sensitivity.
Abstract Photodetectors hold a critical position in optoelectronic integrated circuits, and they convert light into electricity. Over the past decades, high-performance photodetectors (PDs) have been aggressively pursued to enable high-speed, large-bandwidth, and low-noise communication applications. Various material systems have been explored and different structures designed to improve photodetection capability as well as compatibility with CMOS circuits. In this paper, we review state-of-theart photodetection technologies in the telecommunications spectrum based on different material systems, including traditional semiconductors such as InGaAs, Si, Ge and HgCdTe, as well as recently developed systems such as low-dimensional materials (e.g. graphene, carbon nanotube, etc.) and noble metal plasmons. The corresponding material properties, fundamental mechanisms, fabrication, theoretical modelling and performance of the typical PDs are presented, including the emerging directions and perspectives of the PDs for optoelectronic integration applications are discussed.