Optimization of blasting parameters in open cast quarries of El Hassa-Bouira (Northern Algeria)

In recent years, Algeria has known a rapid growth in the construction projects, such as: buildings, roads, and infrastructure, which increased the demand for aggregates production in quarries. However, vibrations and noises generated by blasting operations have a negative impact on the residents living nearby. For this reason, blast tests were performed in the open cast quarries of the company Sarl El Hassa-Bouira (Northern Algeria) using instantaneous electric detonators (IED), micro delays (MDD) and delays (EDD) to minimize the instantaneous load. We also minimized noise and vibration during the blasting. A seismograph allowed us to take further measurements

Predicted rates of merging neutron stars in galaxies

In this work, we compute rates of merging neutron stars (MNS) in galaxies of different morphological type, as well as the cosmic MNS rate in a unitary volume of the Universe adopting different cosmological scenarios. Our aim is to provide predictions of kilonova rates for future observations both at low and high redshift. In the adopted galaxy models, we take into account the production of r-process elements either by MNS or core-collapse supernovae. In computing the MNS rates we adopt either a constant total time delay for merging (10 Myr) or a distribution function of such delays. Our main conclusions are: i) the observed present time MNS rate in our Galaxy is well reproduced either with a constant time delay or a distribution function $\propto t^{-1}$. The [Eu/Fe] vs. [Fe/H] relation in the Milky Way can be well reproduced with only MNS, if the time delay is short and constant. If the distribution function of delays is adopted, core-collapse supernovae as are also required. ii) The present time cosmic MNS rate can be well reproduced in any cosmological scenario, either pure luminosity evolution or a typical hierarchical one, and spirals are the main contributors to it. iii) The spirals are the major contributors to the cosmic MNS at all redshifts in hierarchical scenarios. In the pure luminosity evolution scenario, the spirals are the major contributors locally, whereas at high redshift ellipticals dominate. iv) The predicted cosmic MNS rate well agrees with the cosmic rate of short Gamma Ray Bursts if the distribution function of delays is adopted, in a cosmological hierarchical scenario observationally derived. v) Future observations of Kilonovae in ellipticals will allow to disentangle among constant or a distribution of time delays as well as among different cosmological scenarios

Money in a Theory of Banking

We explore the connection between money, banks, and aggregate credit. We start with a simple real' model without money, where banks make loans repayable in goods and depositors hold claims on the bank payable on demand in goods. Aggregate production may be delayed in the economy. If so, we show that the level of ongoing bank lending, and hence of aggregate future output, can decrease with increases in the real repayment due on deposits: ceteris paribus, the higher the amount due, the more likely there will be insufficient goods, given the delay, to pay depositors, and the more new lending has to be curtailed to make up the shortfall. Thus a temporary delay in production can be exacerbated by banks into a more permanent reduction of total output. A number of inefficiencies including bank failures can result if deposits turn out to be too high. We then introduce money in this model. We show that if demand deposits are repayable in money rather than in goods, banks can be hedged against production delays: under certain circumstances, the price level will rise with delays in production, reducing the real value of the deposits banks have to pay out. But demand deposits payable in money can expose the banks to new risks: the value of money can fluctuate for reasons other than delays in aggregate production. Because deposits are convertible into money on demand, a temporary rise in money demand immediately boosts the interest rate banks have to pay depositors, which in turn boosts the real amounts banks have to repay them. This increase in the real deposit burden can again lead to the curtailment of bank lending and even bank failures. The way to combat these contractionary effects is to infuse more money into the banking system. Our analysis thus makes transparent how changes in the supply of money can work through banks to affect real economic activity, without invoking sticky prices, reserve requirements, or deposit insurance. It also suggests how bank failures could lead to a fall in prices and a contagion of bank failures, as described by Friedman and Schwartz (1963).

Buffer Sizing for 802.11 Based Networks

We consider the sizing of network buffers in 802.11 based networks. Wireless networks face a number of fundamental issues that do not arise in wired networks. We demonstrate that the use of fixed size buffers in 802.11 networks inevitably leads to either undesirable channel under-utilization or unnecessary high delays. We present two novel dynamic buffer sizing algorithms that achieve high throughput while maintaining low delay across a wide range of network conditions. Experimental measurements demonstrate the utility of the proposed algorithms in a production WLAN and a lab testbed.Comment: 14 pages, to appear on IEEE/ACM Transactions on Networkin

Back on the Rails -- Competition and Productivity in State-owned Industry

The importance of Total Factor Productivity (TFP) in explaining output changes is widely accepted, yet its sources are not well understood. We use a proprietary data set on the oor-level operations at the Bhilai Rail and Structural Mill (RSM) in India to understand the determinants of changes in plant productivity between January 2000 and March 2003. During this period there was a 35% increase in output with minimal changes in the stock of physical capital or the number of employees, but sizable reductions in the number and duration of various types of production delays. We model interruptions to the production process as a function of worker characteristics and find that a large part of the avoidable delay reductions are attributable to training. Overall, changes in all delays account for over half the changes in productivity. Our results provide some explanation for the large within-industry di erences in productivity observed in developing countries and also suggest that specic knowledge-enhancing investments can have very high returns. Our approach also provides an example of how detailed data on production processes can be fruitfully used to better understand TFP changes, which have typically been treated as residuals in growth-accounting exercises.Total Factor Productivity (TFP), Plant level data, Competitiveness and trade.

The neutron 'thunder' accompanying the extensive air shower

Simulations show that neutrons are the most abundant component among extensive air shower hadrons. However, multiple neutrons which appear with long delays in neutron monitors nearby the EAS core ('neutron thunder') are mostly not the neutrons of the shower, but have a secondary origin. The bulk of them is produced by high energy EAS hadrons hitting the monitors. The delays are due to the termalization and diffusion of neutrons in the moderator and reflector of the monitor accompanied by the production of secondary gamma-quanta. This conclusion raises the important problem of the interaction of EAS with the ground, the stuff of the detectors and their environment since they have often hydrogen containing materials like polyethilene in neutron monitors. Such interaction can give an additional contribution to the signal in the EAS detectors. It can be particularly important for the signals from scintillator or water tank detectors at km-long distances from the EAS core where neutrons of the shower become the dominant component after a few mcsec behind the EAS front.Comment: 12 pages, 4 figures, accepted by J.Phys.G: Nucl.Part.Phy

On the delivery robustness of train timetables with respect to production replanning possibilities

Measuring timetable robustness is a complex task. Previous efforts have mainly been focused on simulation studies or measurements of time supplements. However, these measurements don't capture the production flexibility of a timetable, which is essential for measuring the robustness with regard to the trains' commercial activity commitments, and also for merging the goals of robustness and efficiency. In this article we differentiate between production timetables and delivery timetables. A production timetable contains all stops, meetings and switch crossings, while a delivery timetable only contains stops for commercial activities. If a production timetable is constructed such that it can easily be replanned to cope with delays without breaking any commercial activity commitments it provides delivery robustness without compromising travel efficiency. Changing meeting locations is one of the replanning tools available during operation, and this paper presents a new framework for heuristically optimising a given production timetable with regard to the number of alternative meeting locations. Mixed integer programming is used to find two delivery feasible production solutions, one early and one late. The area between the two solutions represents alternative meeting locations and therefore also the replanning enabled robustness. A case study from Sweden demonstrates how the method can be used to develop better production timetables

Lifting the Veil: The Face of TFP in an Indian Rail Mill

We use a proprietary data set on the floor-level operations at the Bhilai Rail and Structural Mill (RSM) in India to understand how output rose sharply in response to competitive pressures. Output increases came predominantly from reductions in production delays of various kinds. We model interruptions to the production process as a function of worker characteristics and training and find that a large part of the avoidable delay reductions are attributable to a particular form of training, suggesting that such investments can have very high returns. Our work suggests very high returns to knowledge-enhancing investments in emerging economies.Total Factor Productivity (TFP), plant level data, competitiveness and trade