A 96-Channel FPGA-based Time-to-Digital Converter

We describe an FPGA-based, 96-channel, time-to-digital converter (TDC) intended for use with the Central Outer Tracker (COT) in the CDF Experiment at the Fermilab Tevatron. The COT system is digitized and read out by 315 TDC cards, each serving 96 wires of the chamber. The TDC is physically configured as a 9U VME card. The functionality is almost entirely programmed in firmware in two Altera Stratix FPGA's. The special capabilities of this device are the availability of 840 MHz LVDS inputs, multiple phase-locked clock modules, and abundant memory. The TDC system operates with an input resolution of 1.2 ns. Each input can accept up to 7 hits per collision. The time-to-digital conversion is done by first sampling each of the 96 inputs in 1.2-ns bins and filling a circular memory; the memory addresses of logical transitions (edges) in the input data are then translated into the time of arrival and width of the COT pulses. Memory pipelines with a depth of 5.5 $\mu$s allow deadtime-less operation in the first-level trigger. The TDC VME interface allows a 64-bit Chain Block Transfer of multiple boards in a crate with transfer-rates up to 47 Mbytes/sec. The TDC also contains a separately-programmed data path that produces prompt trigger data every Tevatron crossing. The full TDC design and multi-card test results are described. The physical simplicity ensures low-maintenance; the functionality being in firmware allows reprogramming for other applications.Comment: 32 pages, 13 figure

Modeling of MnS precipitation during the crystallization of grain oriented silicon steel

The process of manganese sulfide formation in the course of grain-oriented silicon steel solidification process is described in the paper. Fine dispersive MnS inclusions are grain growth inhibitors and apart from AlN inclusions they contribute to the formation of a privileged texture, i.e. Goss texture. A computer simulation of a high-silicon steel ingot solidification with the use of author’s software has been performed. Ueshima model was adapted for simulating the 3 % Si steel ingot solidification. The calculations accounted for the back diffusion effect according to Wołczyński equation. The computer simulation results are presented in the form of plots representing the process of steel components segregation in a solidifying ingot and curves illustrating the inclusion separation process

Modelling of non-metallic particles motion process in foundry alloys

The behaviour of non-metallic particles in the selected composites was analysed, in the current study. The calculations of particles floating in liquids differing in viscosity were performed. Simulations based on the Stokes equation were made for spherical SiC particles and additionally the particle size influence on Reynolds number was analysed.The movement of the particles in the liquid metal matrix is strictly connected with the agglomerate formation problem.Some of collisions between non-metallic particles lead to a permanent connection between them. Creation of the two spherical particles and a metallic phase system generates the adhesion force. It was found that the adhesion force mainly depends on the surface tension of the liquid alloy and radius of non-metallic particles

Modelling of the crystallization front – particles interactions in ZnAl/(SiC)p composites

The presented work focuses on solid particle interactions with the moving crystallization front during a solidification of the metal matrix composite. The current analyses were made for silicon carbide particles and ZnAl alloy with different additions of aluminium. It was found, that the chemical composition of the metal matrix influences the behaviour of SiC particles. At the same time calculations of the forces acting on a single particle near the crystallization front were performed. For each alloy type the critical conditions that determine whether particle will be absorbed or pushed, were specified

Family‐ and population‐level responses to atmospheric CO2 concentration: gas exchange and the allocation of C, N, and biomass in Plantago lanceolata (Plantaginaceae)

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142197/1/ajb21080.pd

Time of flight measurements based on FPGA using a breast dedicated PET

In this work the implementation of a Time-to-Digital Converter (TDC) using a Nutt delay line FPGA-based and applied on a Positron Emission Tomography (PET) device is going to be presented in order to check the system’s suitability for Time of Flight (TOF) measurements. In recent years, FPGAs have shown great advantages for precise time measurements in PET. The architecture employed for these measurements is described in detail. The system developed was tested on a dedicated breast PET prototype, composed of LYSO crystals and Positive Sensitive Photomultipliers (PSPMTs). Two distinct experiments were carried out for this purpose. In the first test, system linearity was evaluated in order to calibrate the time measurements, providing a linearity error of less than 2% and an average time resolution of 1.4 ns FWHM. The second set of measurements tested system resolution, resulting in a FWHM as good as 1.35 ns. The results suggest that the coincidence window for the current PET can be reduced in order to minimize the random events and thus, achieve better image qualityAguilar, A.; García Olcina, R.; Martos, J.; Soret, J.; Torres-Pais, J.; Benlloch Baviera, JM.; González Martínez, AJ.... (2014). Time of flight measurements based on FPGA using a breast dedicated PET. Journal of Instrumentation. 9:0-8. doi:10.1088/1748-0221/9/05/C05012S08

Nutrient abundance and variability from soils in the coast of king George Island

The goal of the study was to assess the levels of plant available nutrients in the soils of the Antarctic oasis of Point Thomas in the vicinity of Polish Antarctic Station H. Arctowski. Antarctic soils are undergoing transformations in the era of climatic changes and it is important to quantify changes in soil properties and determine the relationships between soil properties and ecological gradient. Total C and N were determined using CN analyser, mineral forms of nitrogen were determined colorimetrically, plant available P and K was analysed with Egner-Riehm method, Mg with Schachtschabel method and Fe, Mn, Cu, Zn were determined in 1M KCl using AAS (Atomic Absorption Spectrometry) method. The amounts of analysed compounds were dependent on organic matter, which was influenced by plant succession, and in some sites by the activity of seabirds. Most of organic matter was accumulated in the vicinity of penguin colony. All studied soils were abundant in plant available forms of studied macro- and micronutrients. In addition to translocation of biogens (mainly N and P) from the sea to the land by piscivorous birds, a dispersion of biogens on the entire ice-free area occurs. It is related to the occasional appearance of scua as well as the eolian topsoil dust input