SplitTrie: A Fast Update Packet Classification Algorithm with Trie Splitting

Software Defined Network (SDN) currently is widely used in the implementation of new network technologies owing to its distinctive advantages. In changeable SDN environments, the update performance of SDN switches has significant importance for the overall network performance because packet processing could be interrupted by ruleset updating in SDN switches. In order to guarantee high update performance, we propose a new classification algorithm, SplitTrie, based on trie structures and trie splitting. SplitTrie splits rulesets according to the field type vectors of rules. The splitting can improve the update performance because it reduces the trie structure sizes. Experimental results demonstrated that SplitTrie could achieve 20 times of update speed in the complex rulesets comparing the method without trie splitting.

IEA 4E SSL ANNEX INTERLABORATORY COMPARISON OF GONIOPHOTOMETERS MEASURING SOLID STATE LIGHTING PRODUCTS – RESULTS

The global interlaboratory comparison (IC 2017) on measurements of solid-state lighting (SSL) products with goniophotometers was conducted under the International Energy Agency 4E Solid State Lighting Annex with 36 participating laboratories from 19 countries with a total of 42 goniophotometric instruments including mirror-type, near-field type and source-rotating type goniophotometers. A narrow-beam LED lamp and three different types of LED luminaires, including a street lighting luminaire, were used as comparison artefacts for measurements of 16 different quantities. These included electrical, photometric, and colorimetric quantities, and goniophotometric quantities such as centre beam intensity, beam angle, partial flux (15° cone angle), and angular colour uniformity. CIE S 025 was used as the test method. The results demonstrated overall good agreement on luminous flux and colour quantities, however, larger variations and various problems were identified in goniophotometric quantity results. Near-field type and source-rotating type goniophotometers showed equivalent accuracies overall to those of far-field mirror type goniophotometers.

Differentiating lightning in winter and summer with characteristics of wind-field and mass-field

Lightning in winter (December, January, February, DJF) is rare compared to lightning in summer (June, July, August, JJA) in central Europe. The conventional explanation attributes the scarcity of winter lightning to seasonally low values of variables that create favorable conditions in summer. Here we systematically examine whether different meteorological processes are at play in winter. We use cluster analysis and principal component analysis and find physically meaningful groups in ERA5 atmospheric reanalysis data and lightning data for northern Germany. Two sets of conditions emerged: Wind-field-dominated and mass-field (temperature) dominated lightning conditions. Wind-field type lightning is characterized by increased wind speeds, high cloud shear, large dissipation of kinetic energy in the boundary layer, and moderate temperatures. Clouds are close to the ground and a relatively large fraction of the clouds is warmer than −10 °C. Mass-field type lightning is characterized by increased convective available potential energy (CAPE), the presence of convective inhibition (CIN), high temperatures, and accompanying large amounts of water vapor. Large amounts of cloud-physics variables related to charge separation such as ice particles and solid hydrometeors further differentiate both mass-field and wind-field lightning. Winter lightning is wind-field driven whereas in summer lightning is mostly mass-field driven with a small fraction of cases being wind-field driven. Consequently, typical weather situations for wind-field lightning in the study area in northern Germany are strong westerlies with embedded cyclones. For mass-field lightning, the area is typically on the anticyclonic side of a southwesterly jet.