MODELING OF SYNCHRONIZATION OF QUASI-RANDOM AFTERMATH OF A LARGE PERIOD IN CONDITIONS OF EXTERNAL DESTRUCTIVE INFLUENCES

A boundary assessment of the probability of non-acceptance of the test segment when synchronizing the quasi-random sequence of a large period of digital high-speed radio systems in conditions of destructive influences, taking into account all the test segments at the analysis interval in order to increase the probability of phasing of the KSPBP sensors, has been developed.

Homogeneous and automated cooling of a mould segment by multiple water jet impingement and a cross air flow

Multiple water jets and a cross airflow are used to cool a mould segment in a homogeneous and automated manner. An average temperature difference of less than 3 °C and a maximum temperature difference of less than 6 °C were obtained along the length of the surface of the test segment during the entire duration of the cooling process as opposed to the traditional channel cooling approach were the mean and maximum temperature differences increase over time. The top surface of the test segment represents the mould/part interface which is of interest in this study. Using model predictive control (MPC) and a data driven predictive model, the cooling speed of the test segment's top surface was able to be maintained within ± 5 °C of the cooling ramp imposed. The results were compared to the results obtained when using a simpler On/Off algorithm for automated cooling. Compared to the simpler On/Off algorithm, there was an improvement in the accuracy of the cooling ramp with respect to its reference value of over 30 % for most cooling ramps tested (5 – 25 °C/min). A parametric study on the influence of the flow rates of the fluids on the cooling speed of the test segment's surface was also conducted.

Influence of the Conditions of Corotating Twin-Screw Extrusion for Talc-Filled Polypropylene on Selected Properties of the Extrudate

The aim of the study was to determine the effect of the application of processing screws with a modified test segment in a corotating twin-screw extruder on selected properties of talc-filled polypropylene extrudate. The test segment was built of trilobe kneading elements and its design modifications refered to changing the distance between the kneading elements and the angle of positions of kneading elements that are relative to each other. The performed tests included the production of extrudate with various degrees of talc-filling using five design solutions of the test segment and then measurements of selected properties, such as tensile strength, elongation at maximum tensile stress, and melt flow rate. Structural studies using scanning electron microscope (SEM) and differential scanning calorimetry (DSC) were also carried out. The study includes not only the description of experimental results but also the determination of empirical models describing the dependence of the properties of the obtained extrudate on the conditions of the extrusion process and the design features of the test segment.

Experimental Evaluation of Blasting Near Pipelines

Construction blasting was proposed as a technique to create a trench for a new pipeline within the right-of-way (ROW) of an existing vintage pipeline where soil conditions consisted primarily of rock. Several field experiments were conducted to assess the potential loading conditions that the vintage pipeline could experience due to various blasting configurations as part of the nearby construction process. Two test pipe segments were constructed from segments removed from the vintage pipeline for use in these experiments. Each test segment contained two vintage bell-bell chill ring girth welds (GW) and were pressurized to operating conditions of the vintage pipeline for the duration of all blasting. Groups of eight resistive strain gages were bonded around the exterior surface of three distinct locations on each test segment. The three locations include one pipe body location and each of the two welds on each segment. Four separate experiments were conducted with each experiment focusing on a unique combination of trench backfill material, compaction level and separation distance from the test pipe segments and the explosive charges. The primary objective throughout these four experiments was to monitor and record the behavior of buried test pipe sections due to nearby blasting activities. Long range 3-dimentional (3D) laser scanning equipment was used to track movement of each test segment from test to test. High-speed video equipment was also employed to capture each blast. The high-speed video provided additional details on the blast energy transfer, verification of individual charge initiation as well as pipeline test segment movement where each pipeline segment was exposed. Peak particle velocity measurements were taken during each test blast. Strain data collected during each test was used to assess potential damage to the vintage pipeline test segments as a result of blasting. The combined information collected from the in-field testing showed that elevated strains and stresses may be observed during blasting activities near pipelines.

A Study on Subgrade Pressure Differential Over Regions of Known Substructure Transition as it Relates to Track Geometry

The support structure beneath railroad tracks may appear to be a simple layering of various materials, but rather, it is a complex system working together to distribute the load of passing trains. It is paramount that this structure maintain its designed support properties not only to preserve component life expectancy but to maintain the safety of the trains traveling over the rails. During normal operations, track geometry, as evaluated through the standard deviation of various track geometry channels, tends to degrade over time. This is a byproduct of the cyclical loading applied to the track structure by passing trains causing the slow compacting and settling of the ballast and sub-structure. Assuming all variables are held constant, a regular maintenance schedule should bring track geometry back into acceptable limits, but this is generally not the case in real life. In the event that the subgrade cannot support and distribute the pressure caused from the passing train successfully, accelerated track geometry degradation can take place. This accelerated degradation can be further increased when there exists a transition between support strengths which can lead to increased dynamic loading. A case study in sub-structure pressure management has been devised and applied to a high speed rail line. During a recent track renewal operation where track was maintained down to the subgrade, pressure transducers were placed within the sub-grade layer under both the left and right rails, inside and outside of track regions where sub-structure management has been applied. This test segment was monitored over a period of one year with both pressure and track geometry data being recorded at regular intervals. This paper will explore the relationship between sub-structure pressure and local track geometry measurements as it relates to the monitored test segment with a region of known subgrade management transition. Numerous numerical techniques will be applied to understand the change over time of the subgrade pressure distribution capability (measured as pressure beneath the rail) and the degradation of various track geometry channels individually over time. Correlation of the pressure data to track geometry data will also be done using both raw data and data processed using numerical techniques. This will lead to an understanding of how the quality of the track support structure, specifically the track support structure’s ability to distribute pressure, can affect the magnitude and degradation rates of various track geometry channels.

Investigation of biofilm structure, flow patterns and detachment with magnetic resonance imaging

Detachment of biomass from biofilms is still a nearly unknown process which has to be investigated in more detail. Magnetic resonance imaging (MRI) is a promising method which supplies information on the structural data of the biofilm, its surface and the hydrodynamic conditions at the bulk/biofilm interface. Both the structural data and the shear stress are key parameters for understanding biofilm detachment. In this paper a fast quantitative MRI technique was used to investigate the detachment from a heterotrophic biofilm which was grown in a tube reactor. The investigated biofilm was cultivated in a test segment (length 12 cm, diameter 7 mm) of a tube reactor at a constant Reynolds number of 3,000 and a substrate load from 6 g glucose/m2 and day. For the MRI experiments, the test segment with a biofilm of 1,200 μm thickness was connected to the flow loop and placed inside the NMR magnet. During the experiment different hydrodynamic conditions were adjusted for two minutes (Reynolds number Re: 3,000, 4,000, 5,000, 6,000, 7,000, >9,000). Flow velocity and relaxation time were then measured at laminar flow conditions. The MR images show very impressively the increasing detachment of biomass from the biofilm surface with increasing Re. After the last step (Re > 9,000) only a thin biofilm of about 200 μm thickness with a very homogeneous surface remained in the test tube.

The Activation of a Neocentromere in Drosophila Requires Proximity to an Endogenous Centromere

The centromere is essential for proper segregation and inheritance of genetic information. Centromeres are generally regulated to occur exactly once per chromosome; failure to do so leads to chromosome loss or damage and loss of linked genetic material. The mechanism for faithful regulation of centromere activity and number is unknown. The presence of ectopic centromeres (neocentromeres) has allowed us to probe the requirements and characteristics of centromere activation, maintenance, and structure. We utilized chromosome derivatives that placed a 290-kilobase “test segment” in three different contexts within the Drosophila melanogaster genome—immediately adjacent to (1) centromeric chromatin, (2) centric heterochromatin, or (3) euchromatin. Using irradiation mutagenesis, we freed this test segment from the source chromosome and genetically assayed whether the liberated “test fragment” exhibited centromere activity. We observed that this test fragment behaved differently with respect to centromere activity when liberated from different chromosomal contexts, despite an apparent sequence identity. Test segments juxtaposed to an active centromere produced fragments with neocentromere activity, whereas test segments far from centromeres did not. Once established, neocentromere activity was stable. The imposition of neocentromere activity on juxtaposed DNA supports the hypothesis that centromere activity and identity is capable of spreading and is regulated epigenetically.