4,199 research outputs found
Threshold Verification Technique for Network Intrusion Detection System
Internet has played a vital role in this modern world, the possibilities and
opportunities offered are limitless. Despite all the hype, Internet services
are liable to intrusion attack that could tamper the confidentiality and
integrity of important information. An attack started with gathering the
information of the attack target, this gathering of information activity can be
done as either fast or slow attack. The defensive measure network administrator
can take to overcome this liability is by introducing Intrusion Detection
Systems (IDSs) in their network. IDS have the capabilities to analyze the
network traffic and recognize incoming and on-going intrusion. Unfortunately
the combination of both modules in real time network traffic slowed down the
detection process. In real time network, early detection of fast attack can
prevent any further attack and reduce the unauthorized access on the targeted
machine. The suitable set of feature selection and the correct threshold value,
add an extra advantage for IDS to detect anomalies in the network. Therefore
this paper discusses a new technique for selecting static threshold value from
a minimum standard features in detecting fast attack from the victim
perspective. In order to increase the confidence of the threshold value the
result is verified using Statistical Process Control (SPC). The implementation
of this approach shows that the threshold selected is suitable for identifying
the fast attack in real time.Comment: 8 Pages, International Journal of Computer Science and Information
Securit
High-precision calculations of In I and Sn II atomic properties
We use all-order relativistic many-body perturbation theory to study 5s^2 nl
configurations of In I and Sn II. Energies, E1-amplitudes, and hyperfine
constants are calculated using all-order method, which accounts for single and
double excitations of the Dirac-Fock wave functions.Comment: 10 pages, accepted to PRA; v2: Introduction changed, references adde
Influence of built form in urban ventilation assessment of tropical cities with weak wind conditions
Urban ventilation is recognized as effective countermeasure on air pollution and urban heat island, yet most tropical urban areas receive low annual mean wind velocity thus lessening potential for urban ventilation. Effect of built form on resulting mean wind velocity at pedestrian-level was analyzed through computational fluid dynamics (CFD) to assess effectiveness in urban ventilation of tropical cities with weak wind conditions based on three heterogeneous built form of Kampung Baru, Taman Keramat and Pantai Dalam which located in the city of Kuala Lumpur for wind direction from south and west. The urban density for the built form was characterized by using urban packing density parameter of frontal area ratio, ?f and the urban ventilation was assessed based on availability of pedestrian wind which described using wind velocity ratio, VR. Influence of built form in urban ventilation was found to be significant in affecting the mean wind velocity, where magnitude of VR at pedestrian-level was decreasing as the value of ?f of the built form increases. Suggestions to improve urban ventilation design in major development project are provided based on these findings
Regional analysis using the Geomorphoclimatic Instantaneous Unit Hydrograph
International audienceThe construction of design flood hydrographs for ungauged drainage areas has traditionally been approached by regionalisation, i.e. the transfer of information from the gauged to the ungauged catchments in a region. Such approaches invariably depend upon the use of multiple linear regression analysis to relate unit hydrograph parameters to catchment characteristics and generalised rainfall statistics. The concept of the geomorphological instantaneous unit hydrograph (GIUH), in relating the shape and scale of the catchment transfer function to stream network topology and channel characteristics, offers an alternative methodology. GIUH derivation depends upon a series of assumptions, including that of estimating a "characteristic velocity"; these continue to attract attention and debate. However, if this velocity is expressed in terms of the kinematic wave approximation, the peak and time-to-peak of the IUH may be expressed in terms of a group of catchment and channel characteristics and the intensity of rainfall excess, giving the so-called geomorphoclimatic IUH (GCIUH). Previous studies involving the GCIUH have developed a single IUH relating to the total duration of rainfall excess. In this study, the rainfall excess duration was divided into several (equal) time increments, with separate IUHs being generated for each interval. This quasi-linear approach was applied to 105 storm events from nine catchments in the south-west of England, ranging in size from 6 to 420 (km)2 . The results showed that, providing the time interval chosen is fine enough to capture the shape of the runoff hydrographs, a comparable level of goodness-of-fit can be obtained for catchments covering a range of about 1:75 in area. The modified GCIUH approach as described is therefore recommended for further investigation and intercomparison with regression-based regionalisation methods. Keywords: floods; geomorphology; rainfall-runoff modellin
- …