CIMDS: Adapting Postprocessing Techniques of Associative Classification for Malware Detection

National Science Foundation of China [10771176]; Guangdong Province Foundation [2008A090300017]; U. S. National Science Foundation [IIS-0546280]; IBM FacultyMalware is software designed to infiltrate or damage a computer system without the owner's informed consent (e. g., viruses, backdoors, spyware, trojans, and worms). Nowadays, numerous attacks made by the malware pose a major security threat to computer users. Unfortunately, along with the development of the malware writing techniques, the number of file samples that need to be analyzed, named "gray list,"on a daily basis is constantly increasing. In order to help our virus analysts, quickly and efficiently pick out the malicious executables from the "gray list," an automatic and robust tool to analyze and classify the file samples is needed. In our previous work, we have developed an intelligent malware detection system (IMDS) by adopting associative classification method based on the analysis of application programming interface (API) execution calls. Despite its good performance in malware detection, IMDS still faces the following two challenges: 1) handling the large set of the generated rules to build the classifier; and 2) finding effective rules for classifying new file samples. In this paper, we first systematically evaluate the effects of the postprocessing techniques (e. g., rule pruning, rule ranking, and rule selection) of associative classification in malware detection, and then, propose an effective way, i.e., CIDCPF, to detect the malware from the "gray list." To the best of our knowledge, this is the first effort on using postprocessing techniques of associative classification in malware detection. CIDCPF adapts the postprocessing techniques as follows: first applying Chi-square testing and Insignificant rule pruning followed by using Database coverage based on the Chi-square measure rule ranking mechanism and Pessimistic error estimation, and finally performing prediction by selecting the best First rule. We have incorporated the CIDCPF method into our existing IMDS system, and we call the new system as CIMDS system. Case studies are performed on the large collection of file samples obtained from the Antivirus Laboratory at Kingsoft Corporation and promising experimental results demonstrate that the efficiency and ability of detecting malware from the "gray list" of our CIMDS system outperform popular antivirus software tools, such as McAfee VirusScan and Norton AntiVirus, as well as previous data-mining-based detection systems, which employed Naive Bayes, support vector machine, and decision tree techniques. In particular, our CIMDS system can greatly reduce the number of generated rules, which makes it easy for our virus analysts to identify the useful ones

Electrical Signal Guided Ibuprofen Release from Electrodeposited Chitosan Hydrogel

Electrical signal guided drug release from conductive surface provides a simple and straightforward way for advanced drug delivery. In this study, we investigated the ibuprofen release from electrodeposited chitosan hydrogel by applying electrical signals. Specifically, chitosan hydrogel was electrodeposited on titanium plate and used as a matrix for ibuprofen load and release. The release of ibuprofen from the chitosan hydrogel on titanium plate was pH sensitive. By applying a positive or negative electrical potential, the release rate of ibuprofen from the electrodeposited chitosan can be facilely controlled. Thus, coupling chitosan electrodeposition and electrical signal control spurs new possibilities for biopolymeric coating and drug elution on conductive implants

Space-Time Evolution Characteristics of Deformation and Failure of Surrounding Rock in Deep Soft Rock Roadway

In view of the problems of large deformation of surrounding rock, high in-situ stress, and serious soft fracture of rock stratum in deep soft rock roadway, the instability deformation failure mode of deep soft rock roadway is analyzed theoretically. The FLAC3D software is used to establish a three-dimensional numerical model of surrounding rock damage under load, and to study the displacement, stress, and plastic expansion process of damage and failure evolution in the surrounding rock of the roadway. The mechanical response mechanism of deep soft rock roadway surrounding rock bending deformation, elastoplastic transformation, and unloading failure is verified by MATLAB numerical analysis, and the space-time evolution characteristics of soft rock deformation and failure are revealed. The results show that the surrounding rock of deep soft rock roadway has many failure modes, such as obvious displacement and deformation, high stress concentration, and intensified plastic transformation in the surrounding rock. The vertical stress in the surrounding rock is concentrated at the direct top and bottom, and the horizontal stress is concentrated at the roadway side and bottom; plastic deformation and failure first appeared at the roadway side, and then extended to other parts. The research conclusion provides an important reference for surrounding rock control and roof management of high-stress soft rock roadway under deep excavation disturbance

Study on Space–Time Evolution Law and Mechanism of Instability Failure of Deep High-Stress Overburden Rock

In order to explore the fracture law and structural evolution characteristics of overlying strata in deep high-stress mining, according to the geometric characteristics and mechanical causes of overlying strata in different mining stages of the stope, four stages of overlying strata structure model are established and analyzed in turn. According to the characteristics of the overburden load transfer path in the deep high-stress stope, the fracture law and macroscopic mechanical response of overburden are analyzed by MATLAB and PFC2D numerical simulation method. The evolution model of overburden structure and load transfer in ‘four stages and three modes’ of the deep high-stress stope is constructed, and the stage fracture effect of ‘beam, plate and arch’ is put forward. The results show that the overburden rock is a fixed beam structure before the initial weighting. After the initial weighting, it evolves into a plate structure with three sides fixed and one side simply supported. After the periodic weighting, the overburden rock structure further evolves into a plate structure with one side fixed and three sides simply supported. After full mining, the overburden rock forms an arch structure, and the load is transmitted by the beam–plate–arch path. The findings of the study provide an important basis for exploring the nature of overburden transport and load transfer in deep high-stress quarries and strengthening overburden prevention and control

Taking the place of perylene diimide : perylene tetracarboxylic tetraester as a building block for polymeric acceptors to achieve higher open circuit voltage in all-polymer bulk heterojunction solar cells

As strong electron acceptors, perylene diimides (PDI) have been widely utilized to prepare polymeric acceptors with an alternating donor-acceptor (D-A) structure for all-polymer solar cell applications, and which are used to provide low open circuit voltage (V-oc). Cyclic voltammetry measurements reveal that both the HOMO and LUMO levels of a structurally related analogue to PDI, perylene tetracarboxylic tetraester (PTTE), are 0.3 eV higher than those of the corresponding PDI. It was envisioned that replacing PDI by the weaker electron acceptor of PTTE in making polymeric acceptors with D-A structure could help to raise the LUMO level of the resultant polymers, which would lead to a higher V-oc when these PTTE based polymers are used as acceptors in all-polymer solar cell devices. In this work, a new conjugated alternating copolymer, polygperylene tetracarboxylic tetra(2-hexyldecyl)ester-1,7-diyl]-alt-5,5 ''-(2,2':5',2 ''-terthiophene)) (PPTTE-TerT), was synthesized via Stille coupling reaction and characterized as an electron acceptor. The copolymer shows good solubility in common aliphatic organic solvents and good thermal stability. Differential scanning calorinnetry (DSC) and grazing incident X-ray diffraction (GIXRD) measurements indicate that the copolymer at solid state is amorphous. PPTTE-TerT has a relatively broad absorption in the visible region from 400-650 nm with an optical band gap of 1.91 eV. The energy levels of HOMO and LUMO derived from the onset of the first oxidation and reduction potential of the cyclic voltammograms are at -5.6 and -3.54 eV, respectively. All-polymer solar cells of regioregular poly(3-hexylthiophene) (RR-P3HT) as the donor and PPTTE-TerT as the acceptor at an optimized donor-acceptor weight ratio of 1 : 0.7 achieved the best power conversion efficiency of 0.76%. The V-oc is 0.83 V, the short-circuit current (J(sc)) is 2.38 mA cm(-2) and the fill factor (FF) is 0.34 under 1 sun (100 mW cm(-2)) AM1.5G solar illumination. The V-oc value is about 0.3 V higher than that of the all-polymer solar cell based on blending RR-P3HT with the acceptor copolymer comprised of alternating PDI-terthiophene units, which is consistent with the fact that the LUMO level of PTTE is 0.3 eV higher than that of PDI. These results indicate that PTTE is a promising electron-accepting unit to construct polymeric acceptors to be used in all-polymer BHJ solar cells

Tailoring vertical phase distribution of quasi-two-dimensional perovskite films via surface modification of hole-transporting layer

Vertical phase distribution plays an important role in the quasi-two-dimensional perovskite solar cells. So far, the driving force and how to tailor the vertical distribution of layer numbers have been not discussed. In this work, we report that the vertical distribution of layer numbers in the quasi-two-dimensional perovskite films deposited on a hole-transporting layer is different from that on glass substrate. The vertical distribution could be explained by the sedimentation equilibrium because of the colloidal feature of the perovskite precursors. Acid addition will change the precursors from colloid to solution that therefore changes the vertical distribution. A self-assembly layer is used to modify the acidic surface property of the hole-transporting layer that induces the appearance of desired vertical distribution for charge transport. The quasi-two-dimensional perovskite cells with the surface modification display a higher open-circuit voltage and a higher efficiency comparing to reference quasi-two-dimensional cells