Zuverlässigkeitsanalyse für technische Systeme unter Berücksichtigung der behebbaren und nicht behebbaren Ausfälle

Forschung im Ingenieurwesen - Im vorliegenden Beitrag wird eine Zuverlässigkeitsanalyse für moderne technische Systeme unter Berücksichtigung der behebbaren und nicht behebbaren...     

Investigation of the optical properties of P,As and Sb incorporated AlGaX alloys using full potential linearized augmented plane wave method

Dielectric function, absorption coefficient, reflectivity, optical conductivity, energy loss spectra, index of refraction and extinction coefficient of AlGaX (X=P, As, Sb) in rocksalt phase, are calculated using full potential linearized augmented plane wave (FP-LAPW) method. All optical parameters are calculated in the incident photon energy range 0–25 eV. The maximum value of optical conductivity observed is 15 000 S. Index of refraction has a maximum value of 4.6. A decrease in the absorption coefficient and optical conductivity is observed when X is replaced by P, As and Sb. The extinction coefficient increases when P is replaced by As and Sb. The high value (n=4.6$n=4.6$) of the index of refraction shows that AlGaX is a suitable alloy to be used in making advanced optical devices.     

Observation of unconventional anomalous Hall effect in epitaxial CrTe thin films

We have studied the magnetic and electrical transport properties of epitaxial NiAs-type CrTe thin films grown on SrTiO₃(111) substrates. Unlike rectangle hysteresis loops obtained from magnetic measurements, we have identified intriguing extra bump/dip features from anomalous Hall experiments on the films with thicknesses less than 12 nm. This observed Hall anomaly is phenomenologically consistent with the occurrence of a topological Hall effect(THE) in chiral magnets with a skyrmion phase. Furthermore, the THE contribution can be tuned by the film thickness, showing the key contribution of asymmetric interfaces in stabilizing Néel-type skyrmions. Our work demonstrates that a CrTe thin film on SrTiO₃(111) substrates is a good material candidate for studying real-space topological transport.

Open image in new window

     

Vector Based Genetic Algorithm to optimize predictive analysis in network security

A new Intrusion Detection System (IDS) for network security is proposed making use of a Vector-Based Genetic Algorithm (VBGA) inspired by evolutionary approaches. The novelty in the algorithm is to represent chromosomes as vectors and training data as matrices. This approach allows multiple pathways to calculate fitness function out of which one particular methodology is used and tested. The proposed method uses the overlap of the matrices with vector chromosomes for model building. The fitness of the chromosomes is calculated from the comparison of true and false positives in test data. The algorithm is flexible to train the chromosomes for one particular attack type or to detect the maximum number of attacks. The VBGA has been tested on two datasets (KDD Cup-99 and CTU-13). The proposed algorithm gives high detection rate and low false positives as compared to traditional Genetic Algorithm. A detailed comparative analysis is given of proposed VBGA with the traditional string-based genetic algorithm on the basis of accuracy and false positive rates. The results show that vector based genetic algorithm provides a significant improvement in detection rates keeping false positives at minimum.     

A hybrid genetic algorithm for machine-part grouping

Cellular manufacturing (CM), which incorporates the flexibility of job shops and high production rate of flow lines, has been seen as a promising alternative for batch type production. Although CM provides great benefits, the design of CM is quite complex for real world problems. The main problem in the design of a CM is the formation of machine groups and corresponding part families. This paper aims at developing an approach that combines a local search heuristic (LSH) with genetic algorithm (GA). The approach has been tested on a number of problems from the literature. The results show that new approach not only converges to the best solution in the earlier generations but also produces solutions that are as accurate as any of the results reported, so far, in literature. Also, in certain cases the results produced by this technique are even better than the previously reported results.     

A Hybrid Approach for Network Intrusion Detection

Due to the widespread use of the internet and smart devices, various attacks like intrusion, zero-day, Malware, and security breaches are a constant threat to any organization's network infrastructure. Thus, a Network Intrusion Detection System (NIDS) is required to detect attacks in network traffic. This paper proposes a new hybrid method for intrusion detection and attack categorization. The proposed approach comprises three steps to address high false and low false-negative rates for intrusion detection and attack categorization. In the first step, the dataset is preprocessed through the data transformation technique and min-max method. Secondly, the random forest recursive feature elimination method is applied to identify optimal features that positively impact the model's performance. Next, we use various Support Vector Machine (SVM) types to detect intrusion and the Adaptive Neuro-Fuzzy System (ANFIS) to categorize probe, U2R, R2U, and DDOS attacks. The validation of the proposed method is calculated through Fine Gaussian SVM (FGSVM), which is 99.3% for the binary class. Mean Square Error (MSE) is reported as 0.084964 for training data, 0.0855203 for testing, and 0.084964 to validate multiclass categorization.     

Synthesis and Investigation of Electrical Properties of Strontium Metal-Doped Hexaferrite Nanoparticles

Journal of Superconductivity and Novel Magnetism - In the current work cobalt, magnesium and lithium dopant substitution is performed in series of SrFe(12-2x)(Co,Mg,Li)xO19 (for...     

Elevated-Temperature Annealing Effects on AlGaN/GaN Heterostructures

The effect of high-temperature annealing of undoped AlGaN/GaN heterostructures on different substrates was systematically studied between 1100°C and 1230°C. An AlN spacer layer was found to add stability to structures on sapphire substrates. AlGaN/GaN heterostructures on SiC substrates demonstrated excellent robustness for the temperature range studied, maintaining their mobility, sheet resistance, and sheet concentration values, even after annealing. A silicon nitride, SiN _x , capping layer was found to assist in minimizing surface roughness during annealing and maintaining the electrical characteristics of the heterostructures. AlGaN/GaN heterostructures on SiC substrates showed a 20% decrease in mobility for uncapped samples compared with SiN _x -capped samples.     

Physiological and biochemical responses of Brassica napus L. to drought-induced stress by the application of biochar and Plant Growth Promoting Rhizobacteria

Climate change induces biotic and abiotic stress conditions, which badly affect the yield of crops with leading to the biochemical and physiological damages to plants. Biochar and plant growth promoting rhizobacteria (PGPR) alleviate the effect of drought condition therefore a field study was conducted to examine the single and combine application of drought tolerant Pseudomonas sp. and Staphylococcus sp. with biochar of Morus alba L. wood to mitigate the adverse effects of drought stress in two genotypes of Brassica napus L. including Punjab sarson and westar. Physioco-chemical analysis of biochar showed 5.4 cmol/kg cation exchange capacity, 6.9 ds/m electrical conductivity, pH of 9.6, 0.50 g/cm³ bulk density, and organic carbon 3.64%. Synergistic application of PGPR and biochar developed the plant antioxidant enzyme including catalase (CAT) and ascorbate peroxidase (APX) and also enhanced the content of photosynthetic pigments like chlorophyll pigments, carotenoids content, and anthocyanin content. Scanning electron microscope (SEM) study revealed that biochar and PGPR improved epidermal vigor and stomatal physiology. Malondialdehyde (MDA), hydrogen peroxide (H₂O₂), APX, and osmolyte content including proline increased in drought stress, which were then decreased by these growth promoters. These results are very important as they illustrate the potential of PGPR and biochar to alleviate the adverse consequences of drought stress and offer a way of increasing the tolerance of B. napus L. plant grown under induced drought stress.