Search

The need to eliminate bottlenecks to port operations in Nigeria was a fundamental goal of the port privatization about 2 decades ago. Current trends in ports management; however, suggest existence of numerous inefficiency challenges reflected in long ship turnaround time, increasing trend of cargo dwell time, high cargo pilferage risk rate, poor condition of port infrastructure and superstructure, multiple charges and government agencies, cumbersome cargo clearance & examination procedures, port congestion related delays particularly in Apapa and Onne ports, etc. The study identifies the decisive port-related factors constraining the flow of shipping trade in Nigerian ports using a survey to obtain data on the influence of the identified factors on the flow of shipping trade in Nigerian ports. The Principal Component Analysis (PCA) was used to analyze the data obtained. The results indicate that high cargo pilferage risk profile, long ship turnaround time and increasing trend of cargo dwell time constitute the significant port-related factors constraining the flow of shipping in Nigerian ports. It can be concluded that terminal operators should prioritize solutions to the problems of high cargo pilferage risk profile, long ship turnaround time and increasing cargo dwell time, which constitute the major constraints to the flow of shipping trade.

Travelers along the Onne-seaport to Eleme-junction road corridor in the hub of the oil and gas industry in Port-Harcourt, Nigeria, have continued to experience very serious traffic congestion travel time delays, culminating into loss of man-hours and declining productivity. This study estimated the economic cost of traffic congestion travel time delay along the corridor, with a view to providing economic justification for developing traffic management policies and road infrastructure, to remedy it. A mixed research approach was adopted in which data was sourced through field survey and from secondary sources. The gross output model was used to estimate the output losses occasioned by productive time losses related to traffic congestion. The study established that the average daily traffic congestion travel time delay along the traffic corridor by travelers in trucks, car, bus and taxi modes are 104.17 minutes, 46.60 minutes, 58.5 minutes and 56.4 minutes respectively. The estimated daily aggregate economic cost of output losses associated with traffic congestion time delay on the corridor is 46049809.8 naira (210923.5USD) for all modes. This justifies any investment in traffic congestion remedial strategies along the route.

This article describes the energy-saving measures in commercial buildings from different perspectives on energy saving in cities. In recent years, improving energy conservation in commercial buildings has become an issue of great importance for the financial well-being of organisations. The study uses the define-measure-analyze-improvecontrol (DMAIC) Six Sigma approach to identify the factors that contribute to increases in electricity consumption. With the increasing shortage of energy, two years’ worth of energy consumption data from a commercial building in South Africa was collected and analyzed using statistical tools. The research findings revealed that the boiler had the highest electricity consumption (38.33 per cent), followed by the kitchen (24.20 per cent) and the rest of the building (37.47 per cent). After applying the DMAIC process, it showed that the electricity consumption of the boiler could be reduced by 6 per cent during the improvement phase. [ABSTRACT FROM AUTHOR]

A fast-timing experiment was performed at the Argonne National Laboratory to measure the lifetimes of the lowest lying states of nuclei belonging to the deformed regions around mass number A≃110 and A≃150. These regions were populated via spontaneous fission of 252Cf and the gamma radiation following the decay of excited states in the fission fragments was measured using 51 Gammasphere detectors coupled with 25 LaBr3:Ce detectors. A brief description of the acquisition system and some preliminary results from the fast-timing analysis of the fission fragment 100Zr are presented. The lifetime value of τ = 840(65) ps was found for the 2+ state in 100Zr consistent within one standard deviation of the adopted value with 791 +26 -35ps. This is associated with a quadrupole deformation parameter of 0.36(2) which is within one standard deviation of the literature value of 0.3556+82 -57.

The commissioning of a new setup for β-delayed neutron measurements was carried out successfully in November-2016, at the RIKEN Nishina Center in Japan. The β-decay half-lives and Pn branching ratios of several isotopes in the 78Ni region were measured. Details of the experimental setup and the first results are given.

AGATA is a 4-pi array of high purity Ge detectors for in-beam gamma-ray spectroscopy based on the novel concepts of pulse shape analysis (PSA) and gamma-ray tracking. Tracking and PSA require the concurrent digitization--at a sampling rate of 100 Msamples/s--of preamplifier signals of the 36-fold segmented Ge crystals composing the array. Locally digitized data are optically transferred to remote pre-processing nodes for pulse energy computation. The design of the front-end readout and level-1 (L1) trigger in AGATA follows a synchronous pipeline model: the detector data are stored in pipeline buffers at the global AGATA frequency, waiting the global L1 decision. A global timing system provides a reference clock and time tag to the digitizers and the pre-processing units by means of a tree of optically connected timing units. Pre-processing nodes are integrated in AdvancedTCA-based carrier cards with full mesh connectivity in the backplane and read-out through pci-express based optical links. The front-end data readout and its integration in the global trigger and synchronization system will be described. Index Terms--AdvancedTCA, digital trigger, distributed synchronization, full mesh readout, Pci-Express.

A gamma-ray tracking algorithm has been implemented and tested, using simulated data, for gamma rays with energies between 0.1 and 2 MeV, and its performance evaluated for a 90-mm-long, 60-mm-diameter, cylindrical, 36 (6 x 6) segment detector. The performance of the algorithm in two areas was determined: Compton suppression and Doppler shift correction. It was found that for gamma rays of energies around 1 MeV, a ratio of photopeak counts to total counts of 2:3 could be obtained using the tracking algorithm, with only a 2% reduction in detection efficiency, compared to the untracked data. Approximately 80% of first interaction points could be correctly identified, enabling a good Doppler shift correction. A detector of the type simulated has recently been delivered, together with a compactPCI digital data acquisition system comprising 36 12-bit, 40-MHz flash ADCs, and 6 200-MHz DSPs. Some initial data has been recorded using this system, and the performance of the tracking algorithm on this real data is comparable to its performance on simulated data.

During 1992-1993 the Nuclear Structure Facility at Daresbury Laboratory hosted phase one of the EUROGAM[1] experimental programme. These were the first nuclear physics experiments to make large scale use of the VXIbus standard for electronics and data acquisition. EUROGAM phase 1 was made up of an array of 45 escape suppressed Germanium (Ge) detectors. It was used for gamma-ray spectroscopy both stand-alone and in conjunction with external detectors including the Daresbury Recoil Separator (RS)[2], isomer detectors and various particle detectors. An overview of the system, details of special VXI cards, the readout and trigger systems for EUROGAM have been previously reported at the 1991 IEEENSS. Here we report on how they worked in real experiments.

The new VXIbus standard was tested for use in the packaging of an Anglo/French gamma ray detector, a high density signal processing and data readout system. The EUROGRAM detector is composed of an array of up to 70 high purity Germanium detectors, each accompanied by a multi-element Bismuth Germanate escape suppression shield and is planned to serve between the 20 millivolt Van der Graaf accelerator at Daresbury and the Vivitron in Strasbourg. Results of the test show that the VXIbus standard is compatible with high-precision, multi-channel spectroscopy amplifiers.

A VME-based readout system was used for the EUROGRAM gamma-ray detection system. Its primary features include its combination of VMEbus and an environment suitable for housing analog electronics. The readout system reads an event's data form acquisition modules within the VMEbus crate using a single, slightly modified, VMEbus block transfer. This set-up allows dense packing of both analogue signal processing and data acquisition electronics within a unified framework.

Recoil decay tagging (RDT) is a very powerful method for the spectroscopy of exotic nuclei. RDT is a delayed coincidence technique between detectors usually at the target position and at the focal plane of a spectrometer. Such measurements are often limited by dead time. This paper describes a novel triggerless data acquisition method, which is being developed for the gamma recoil electron alpha tagging (GREAT) spectrometer, that overcomes this limitation by virtually eliminating dead time. Our solution is a total data readout (TDR) method where all channels run independently and are associated in software to reconstruct events. The TDR method allows all the data from both target position and focal plane to be collected with practically no dead-time losses. Each data word is associated with a timestamp generated from a global 100-MHz clock. Events are then reconstructed in real time in the event builder using temporal and spatial associations defined by the physics of the experiment. Index Terms--Alpha-particle spectroscopy, beta-ray spectroscopy, coincidence circuits, data acquisition, gamma-ray spectroscopy, nuclear physics, triggering.

Beta-delayed proton emission from Mg has been measured at ISOLDE, CERN, with the ISOLDE Decay Station (IDS) setup including both charged-particle and gamma-ray detection capabilities. A total of 27 delayed proton branches were measured including seven so far unobserved. An updated decay scheme, including three new resonances above the proton separation energy in Na and more precise resonance energies, is presented. Beta-decay feeding to two resonances above the Isobaric Analogue State (IAS) in Na is observed. This may allow studies of the 4032.9(2.4)keV resonance in Ne through the beta decay of Mg, which is important for the astrophysically relevant reaction O( $ \alpha$ , $ \gamma$ )Ne . Beta-delayed protons were used to obtain a more precise value for the half-life of Mg, 91.4(1.0)ms. [ABSTRACT FROM AUTHOR]

The UK NuStAR project is the largest nuclear physics project presently funded by the Science Technology Facilities Council (STFC) in UK. The aim of the project is to design, construct and deliver detectors and subdetector systems for FAIR. The main project deliverables are a DESPEC multidetector array for fast timing measurements, a HISPEC ToF detector for mass measurements after the secondary target, and the Si tracker for precise vertex determination in R3B experiments with liquid hydrogen target. [ABSTRACT FROM AUTHOR]

It is planned to install the heavy-ion, low-energy ring TSR, currently at the Max-Planck-Institute for Nuclear Physics in Heidelberg, at the HIEISOLDE facility in CERN, Geneva. Such a facility will provide a capability for experiments with stored, cooled secondary beams that is rich and varied, spanning from studies of nuclear ground-state properties and reaction studies of astrophysical relevance, to investigations with highly-charged ions and pure isomeric beams. In addition to experiments performed using beams recirculating within the ring, the cooled beams can be extracted and exploited by external spectrometers for high-precision measurements. The capabilities of the ring facility as well as some physics cases will be presented, together with a brief report on the status of the project. [ABSTRACT FROM AUTHOR]

UK NuSTAR is the largest Nuclear Physics project, presently funded by the UK Science and Technology Facilities Council. The project aims at construction and delivery of equipment for the R3B, HISPEC, and DESPEC experiments at FAIR. In this contribution, the status of the UK DESPEC work package and related activities will be presented. [ABSTRACT FROM AUTHOR]

Analytical linear electrostatic waves in a magnetized three-component electron-positron-ion plasma are studied in the low-frequency limit. By using the continuity and momentum equations with Poisson's equation, the dispersion relation for the electron-positron-ion plasma consisting of cool ions, and hot Boltzmann electrons and positrons is derived. In the linear regime, the propagation of two possible modes and their evolution are studied. In the cases of parallel and perpendicular propagation, it is shown that these two possible modes are always stable. The present investigation contributes to nonlinear propagation of electrostatic waves in space and the laboratory. [ABSTRACT FROM AUTHOR]

Using a fluid theory approach, this article provides a comparative study on the evolution of nonlinear waves in dusty plasmas, as well as other plasma environments, viz electron-ion, and electron-positron plasmas. Where applicable, relevance to satellite measurements is pointed out. A range of nonlinear waves from low frequency (ion acoustic and ion cyclotron waves), high frequency (electron acoustic and electron cyclotron waves) in electron-ion plasmas, ultra-low frequency (dust acoustic and dust cyclotron waves) in dusty plasmas and in electron-positron plasmas are discussed. Depending upon the plasma parameters, saw-tooth and bipolar structures are shown to evolve. [ABSTRACT FROM PUBLISHER]

Linear electrostatic waves in a magnetized four-component, two-temperature electron–positron plasma are investigated, with the hot species having the Boltzmann density distribution and the dynamics of cooler species governed by fluid equations with finite temperatures. A linear dispersion relation for electrostatic waves is derived for the model and analyzed for different wave modes. Analysis of the dispersion relation for perpendicular wave propagation yields a cyclotron mode with contributions from both cooler and hot species, which in the absence of hot species goes over to the upper hybrid mode of cooler species. For parallel propagation, both electron-acoustic and electron plasma modes are obtained, whereas for a single-temperature electron–positron plasma, only electron plasma mode can exist. Dispersion characteristics of these modes at different propagation angles are studied numerically. [ABSTRACT FROM PUBLISHER]

Nonlinear ion cyclotron and ion-acoustic waves have been studied in an electron–positron–ion plasma. Using Boltzmann distributions for the electrons and positrons and fluid equations for the ions, a set of nonlinear equations in the rest frame of the propagating wave is derived and numerically solved for the electric field. A scan of parameter space reveals a range of solutions for the parallel electric field, from sinusoidal to sawtooth to highly spiky waveforms. The results are compared with satellite observations. [ABSTRACT FROM PUBLISHER]

The arbitrary amplitude Langmuir solitons are investigated in an unmagnetized, warm, relativistic plasma, consisting of electrons and positrons. Both the species are considered to have equal non-relativistic temperatures, but can have arbitrary relativistic drift speeds, and their dynamics are governed by fluid equations. Using the Sagdeev psuedo-potential approach, the effects of drift speed, Mach number, and thermal temperature on the amplitude and width of the Langmuir solitons are investigated. For the parameters considered, only rarefactive solitons are found. These solitons represent dip in electron density or electron holes in the configuration space. Existence domain of the Langmuir solitons is limited by the minimum and maximum Mach numbers for given parameters. An increase in the electron (positron) temperature leads to an increase in the Langmuir soliton amplitude and their half-widths. On the other hand, increasing the electron (positron) drift speeds results in decreasing soliton amplitudes and their half-widths. For some typical parameters corresponding to the pulsar magnetosphere, namely electron density ~106 cm−3 and electron thermal velocity of one-tenth of the velocity of light, the electric field of the Langmuir solitons can be of the order of (3–24)kV/m. The presence of such large amplitude electrostatic solitary structures may accelerate electrons and positrons and also produce fine structures of (1–5) microseconds in pulsar radio emissions. [ABSTRACT FROM PUBLISHER]

An Advanced GAmma Tracking Array (AGATA) symmetric prototype high purity Germanium (HPGe) detector has been tested. The detector was illuminated with a 1 mm collimated, beam of 137Cs (662 keV) gamma rays. The beam was raster scanned across the front and sides of the detector and the charge sensitive preamplifier output pulse shapes from all 37 channels (36 segments plus the centre contact) were digitised and stored for off-line analysis. Rise time and image charge asymmetry magnitudes were measured as a function of interaction position to study the charge transport properties through the crystal volume. These parameters were then utilised as a calibrated look up table with which in-beam data was analysed and Doppler corrected. An average position resolution of approximately 9 mm (FWHM) was achieved with a crude analysis. [ABSTRACT FROM AUTHOR]

A four-channel VERSAmodule Eurocard (VME) with 14 bit, 80 MHz digitizers and powerful on-board processing has been designed, built, and used in tests of digital pulse processing techniques for gamma-ray tracking. This paper explains the background, describes the VME card (known as the GRT4) and presents a 64-channel GRT4 digitizing system which was used to instrument two segmented Germanium detectors during in-beam tests. Results obtained using the GRT4 card are presented as well as some applications. [ABSTRACT FROM AUTHOR]