Automatic thresholding of the gray level of an image is very useful in automated analysis of morphological images, and it represents the first step in many applications in Image understanding. Recently it was shown that by choosing the threshold as the value that maximizes the entropy of the one dimensional histogram of an image, one might be able to separate, effectively, the desired objects from the background. This approach, however, does not take into consideration the spatial correlation between the pixels in an image. Thus, the performance might degrade rapidly as the spatial interaction between pixels becomes more dominant than the gray level values. In this case, it becomes difficult to isolate the object from the background and human interference might be required. This was observed during studies that involved images of the stomach.
This paper describes several algorithms for the detection of small changes between images in nois environment. Specifically two procedures for suc! image processing are introduced. The first is, a nonlinear image processin procedure for reduction and/or suppression of bacigrcund (clutter), and the enhancement of the small, difference between two images. This procedure is based on the newly developed Pontryagin filter and concepts of adaptive noise cancellin and ima e-sequence anal sis. Another rocedure is ayso introiuced but it is Sinear. It is lased on a lattice filter structure. The performacne is evaluated through computer simulations and real images.
This research investigates the feasibility of using dry crushed pomegranate peel waste as thermal insulator to produce light clay bricks. Pomegranate peel waste (PW) is used with different substitution levels of 0%, 5%, 7.5%, 10% and 15% of clay weight. The clay bricks were heated at temperatures of 700, 800, and 900 °C, that resulted in the formation of internal pores due to the combustion of PW. The bulk density, water absorption, porosity, shrinkage, and compressive strength are examined to evaluate the effect of using PW on the physical and mechanical properties of thermal insulation bricks. Also, the investigation of the effect of photocatalytic activity of bricks under sunlight irradiation is carried out. The use of PW increased the thermal conductivity up to 21% at 900 °C, water absorption from 22.6% in cold water to 29.1% in boiling water, density from 2.5% at 800 °C to 7.6% at 900 °C, and shrinkage from 4.3% in linear drying shrinkage to 5.4% in linear firing shrinkage. The heated brick samples at 700 °C showed greater photodegradation efficiency than firing clay at 800 °C and 900 °C. Moreover, the compressive strength decreased with the increase in replacement rate, reaching up to 74% for 15 wt% PW. This study confirms that lightweight heated bricks with low thermal conductivity and a reasonable compressive strength can be made using PW as a pore-forming agent.
This paper presents a new adaptive technique for forecasting the Yen/U.S. Dollar exchange rate. The proposed method assumes a time-varying model to describe the evolution of the exchange rate. Weekly predictions of the Yen/U.S. Dollar rate are dominated by weekly announcements of unexpected changes in the relative unemployment claims between the U.S. and Japan. Monthly predictions are more sensitive to monthly releases of the difference between the expected and announced value of the National Association of Purchasing Managers index. The predictive results of the proposed method are found more accurate than that of conventional ARMA techniques.
We present novel formulas for the determination of the optimal values of the exchange rate and the external (foreign currency) debt. A stochastic differential equation is developed that relates the net worth of an economy to both its exchange rate and level of external debt. Using the martingale optimality principle, the optimal values for the exchange rate and the external debt are derived. Applied to Egypt, we find that its actual nominal exchange rate has stayed above its optimal value since the early 1990s, except for two years, and that the actual external debt-to-net worth ratio is lower than the optimal one for most of the time. Since 2013 the actual external debt-to-net worth ratio is close to the risky levels of the optimal values.
This paper discusses the issue of optimal international reserves in Egypt during the period 1977-2007. We derive, using stochastic control, the optimal level of reserves to maximize the welfare of the society as measured by the utility of the consumption. The paper also presents a new approach to manage international reserves. It is proposed that part of the reserves will be held as risky assets. The risky assets are sensitive to the volatility index (VIX) of the Chicago Board Options Exchange (CBOE). The analysis reveals that the actual normalized level of reserves is in excess of the optimal one. Hence, the study recommends reducing the international reserves to the optimal level. This is almost 25% of the current levels of reserves. We also present a scenario whereby the reserves are reduced by almost half of its existing levels in year 2007. We then invest a small portion, through a sovereign wealth fund, in VIX based options. In case of crisis (sudden stop) the payoff of the options will yield an amount that is almost the same as the kept value of reserves. Following this strategy allows for an opportunity gain in the range of (1-2) % of GDP. Moreover, the study proposes the activation of other institutions role in the society to attract long term investments, maintaining a certain limit of coordination among fiscal and monetary policies and consolidating the norms of ethical standards in the financial system.(ProQuest: ... denotes formulae omitted.)International reserves are both observable and have a market value... Gray, Merton and Bodie 20071. IntroductionRecently, along with the dramatic increase in international reserves in emerging market countries, estimated by more than 60 percent since the Asian financial crisis in 1997 as mentioned by Mendoza (2004), debates about the fitting/optimal amount of reserves for an open economy have gained a new life (Jeanne and Ranciere 2009). Being characterized by weak access to international capital markets, recurrent credit crunches and financial underdevelopment; emerging countries run persistent current account deficits and are vulnerable to foreign investors' insights about the underlying economic and institutional circumstances. Jeasakul (2005) put forward that, since investment decisions are based upon profitability criteria,3 any alterations in these conditions due to financial crisis or turmoil, foreign creditors can suddenly cause capital inflows to come to an end, leading to what Dornbusch, Goldfajn and Valdes (1995) firstly marked as a stop, a term that was further developed analytically in Calvo (1998).1.1 Sudden Stops: Some Stylized FactsMany Asian countries during the late nineties of the last century were hit by currency crises and sudden stops.4 Since then, hoarding international reserves has been the preferential policy of most developing economies (Cheung and Qian 2007; Wijnholds and Sndergaard 2007). Sighted in this light, the sharp augmenting in the amount of reserves held by many emerging markets can be relevant to the rise in the that confronts emerging markets as suggested by Calvo (2002). A moderate probability of globalization hazard can induce emerging markets to self-insure fully by hoarding international reserves, rather than relying on non-reserve options of taking preventative measures. A sudden stop,5 in this context, is a distinctive phenomenon of the crisis wracked in emerging countries during the post of the nineties. Lee (2008) put forward that sudden stops in its essence is a situation under which there is a reversal capital inflows to the country, lack of access to external insurance and hence a sharp current account adjustment on recipient countries. Caballero and Panageas (2005) demonstrate that international financial markets cause the sudden stop and not the emerging economies themselves.On the main features of sudden stops, Mendoza (2008) mentioned three stylized facts that are: (1) Changing direction of international capital flows in a reverse order, (2) reductions in domestic production and absorption, (3) Alterations in asset prices. …
A new approach, based on non-linear time-delay estimation, is described for estimating the elevation angle in the combined presence of specular multipath and receiver noise—a situation that is encountered in the low-angle tracking radar environment. Estimation of the elevation angle is accomplished using the time delay between the signals impinging on the antenna array elements. Thus, the accuracy in the elevation angle estimation is dependent on the accuracy of the time-delay estimation algorithm. The formulation of the problem enables one to find the desired estimates independently of the reflection coefficient, which is a significant result. In the proposed approach, a newly derived non-linear filter due to the author (1986) is used. The filter structure is estimated using the Pontryagin minimum principle and the method of invariant imbedding, and is used to find an estimate for the delayed and undelayed signal. Subsequently, the time delay and the elevation angle are estimated.
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