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arXiv2010

Formulation Of A N-Degree Polynomial For Depth Estimation using a Single Image

The depth of a visible surface of a scene is the distance between the surface and the sensor. Recovering depth information from two-dimensional images of a scene is an important task in computer vision that can assist numerous applications such as object recognition, scene interpretation, obstacle avoidance, inspection and assembly. Various passive depth computation techniques have been developed for computer vision applications. They can be classified into two groups. The first group operates using just one image. The second group requires more than one image which can be acquired using either multiple cameras or a camera whose parameters and positioning can be changed. This project is aimed to find the real depth of the object from the camera which had been used to click the photograph. An n-degree polynomial was formulated, which maps the pixel depth of an image to the real depth. In order to find the coefficients of the polynomial, an experiment was carried out for a particular lens and thus, these coefficients are a unique feature of a particular camera. The procedure explained in this report is a monocular approach for estimation of depth of a scene. The idea involves mapping the Pixel Depth of the object photographed in the image with the Real Depth of the object from the camera lens with an interpolation function. In order to find the parameters of the interpolation function, a set of lines with predefined distance from camera is used, and then the distance of each line from the bottom edge of the picture (as the origin line) is calculated.

cs.CV↗

arXiv2010

Relativistically speaking: Let's walk or run through the rain?

We analyse under a simple approach the problem one must decide the best strategy to minimize the contact with rain when moving between two points through the rain. The available strategies: walk (low speed boost $<<$ $c$) or run (relativistic speed boost $\approx$ $c$).

physics.pop-ph↗

arXiv2011

Negative frequency communication

Spectrum is the most valuable resource in communication system, but unfortunately, so far, a half of the spectrum has been wasted. In this paper, we will see that the negative frequency not only has a physical meaning but also can be used in communication. In fact, the complete description of a frequency signal is a rotating complex-frequency signal, in a complete description, positive and negative frequency signals are two distinguishable and independent frequency signals, they can carry different information. But the current carrier modulation and demodulation do not distinguish positive and negative frequencies, so half of the spectrum resources and signal energy are wasted. The complex-carrier modulation and demodulation, proposed by this paper, use the complex-frequency signal as a carrier signal, the negative and positive frequency can carry different information, so the spectrum resources are fully used, the signal energy carried by complex-carrier modulation is focused on a certain band, so the signal energy will not be lost by the complex-carrier demodulation.

cs.IT↗

arXiv2011

Simple model of photo acoustic system for greenhouse effect

The green house effect is caused by the gases which absorb infrared ray (IR) emitted by the earth. It is worthwhile if we can adjudicate on which gas causes the greenhouse effect in our class. For this purpose, one of our authors, Kaneko has designed an educational tool for testing greenhouse effect \cite{Kaneko}. This system (hereafter abbreviated PAS) is constructed based on photo acoustic effect. Without difficulty and high cost, we can build PAS and check the IR absorption of gas. In this paper we give the simple theoretical basis for this PAS. The amplitude of sound observed in PAS depends on the modulation frequency of IR pulse. Its dependence can be explained by this simple model. Further we show the sound amplitude does not depend on the thermal diffusion, which provides the accuracy of amplitude as the IR absorption rate of the gas. According to this model, sound signal is not the sinusoidal function and it has higher harmonics. The theory and experiment are compared in the third harmonics by spectrum analysis. From this apparatus and theory, students can study not only the greenhouse effect but also the basics of physics.

physics.pop-ph↗

arXiv2012

Fazendo 3D com uma camera so

A simple system to make stereo photography or videos based in just two mirrors was made in 1989 and recently adapted to a digital camera setup.

physics.pop-ph↗

arXiv2011

The Last Workshop on Theoretical Physics in the Soviet Union

Twenty years ago, in October 1990, I found myself attending a workshop on Theoretical Physics in Chernomorka (Ukraine) intended only for Soviet physicists. That trip to the USSR/CCCP as well as the preceding months at CERN were highly surrealistic with plenty of adventures, crucial events and anecdotes, the most amazing one involving Niels Bohr. A few months later the Soviet Union collapsed. In this article I make a personal account on the happenings of 1990, with emphasis on my incursions into the European communist world during, and also before, that year.

physics.gen-ph↗

arXiv2012

Information and the arrow of time

This paper is a discussion about the relationship between time and information. We argue that the direction of arrow of time is related to the directivity of information copying that occurs in Nature.

physics.pop-ph↗

arXiv2016

Geometric Algebra: A natural representation of three-space

Historically, there have been many attempts to produce an appropriate mathematical formalism for modeling the nature of physical space, such as Euclid's geometry, Descartes' system of Cartesian coordinates, the Argand plane, Hamilton's quaternions and Gibbs' vector system using the dot and cross products. We illustrate however, that Clifford's geometric algebra (GA) provides the most elegant description of physical space. Supporting this conclusion, we firstly show how geometric algebra subsumes the key elements of the competing formalisms and secondly how it provides an intuitive representation of the basic concepts of points, lines, areas and volumes. We also provide two examples where GA has been found to provide an improved description of two key physical phenomena, electromagnetism and quantum theory, without using tensors or complex vector spaces. This paper also provides pedagogical tutorial-style coverage of the various basic applications of geometric algebra in physics.

physics.hist-ph↗

arXiv2011

Use of root in vehicular accident reconstruction

The purpose of this article is to introduce the reader to the ROOT data analysis software package, and demonstrate how it may be used to complement one's accident reconstruction analyses.

physics.pop-ph↗

arXiv2018

Trajectories of Rubber Balloons used in Balloon Releases: Theory and Application

Balloon releases are one of the main attractions of many fairs. Helium filled rubber balloons are released to carry postcards over preferably long distances. Although such balloons have been considered in atmospheric sciences and air safety analysis, there is only scarce literature available on the subject. This work intends to close this gap by providing a comprehensive theoretical overview and a thorough analysis of real-life data. All relevant physical properties of a rubber balloon are carefully modelled and supplemented by weather observations to form a self-contained trajectory simulation tool. The analysis of diverse balloon releases provided detailed insight into the flight dynamics and potential optimisations. Helium balloons are found to reach routinely altitudes above 10 km. Under optimal conditions, they could stay more than 24 hours airborne while reaching flight distances close to 3000 km. However, external weather effects reduce the typical lifetime to 2-5 hours.

physics.pop-ph↗

arXiv2011

Four pedagogic exercises

This article describes four innovative pedagogical exercises: (i) The expression for relation between cross sections in the laboratory and the centre of mass systems provided in text books assumes zero or low Q values which needs to be corrected for the most general case when Q value of the reaction is not negligible compared to the masses of interacting nuclei. The general expression derived here can be used for elastic and inelastic cases involving zero, low or even very high Q values. (ii) The equation of oscillatory motion of a massive surface put horizontally on two wheels rotating with equal and opposite angular velocities is established. The time period of oscillation is related to the coefficient of dynamic friction between the surface and the wheels which facilitates the measurement of the coefficient of dynamic friction. (iii) The equation of motion of a fixed torque mass shedding vehicle moving against friction and its velocity at any instant of time are derived. This example is equivalent to motion of a mass shedding rocket moving by applying fixed force against atmospheric friction. (iv) The equation of the path of a missile directed at every instant of time towards a rectilinearly moving target and time taken to hit the target are derived. It provides equation of path for asteroid and comet destructing missiles as conceptualized by NASA projects.

physics.class-ph↗

arXiv2011

Böögg Bang drives global climate change

The Böögg is a large model of a snowman, constructed of inflammable materials and filled with explosives. During the traditional festival of Sechseläuten, which takes place each spring in Zurich, Switzerland, the Böögg is placed atop a wooden pyre, which is set alight. According to popular legend, the time that elapses until the Böögg's head explodes (the "head-bang" time) is said to give a rough forecast of local weather conditions prevailing during the following summer. However, recent research has questioned the validity of this prediction. To study the Böögg's predictive powers, we analyzed the Böögg head-bang time record from 1965-2010 within the context of global climate change. Our analysis shows that the Böögg head-bang time is a good predictor not of short-term local weather, as might be expected from the legend, but of the behavior of the entire global climate system.

physics.pop-ph↗

arXiv2011

Esplorazione Della Terra Incognita Della Fisica Nucleare: Nuclei Con Alone, Nuclei "A Grappoli", Nuclei Borromeani e Altre Stranezze Esotiche!

English: If the current status of theoretical and experimental knowledge in Nuclear Physics could be reduced to a geographical chart or a planisphere, then our epoch would be in some respect comparable to the end of the Medieval age and in other to the beginning of the Reinassance: epochs in which, together with the consolidated knowledge of the Old World, there have been great and revolutionary expeditions as the discovery of America or the periplus of Cape of Good Hope, explorations aimed at reaching the limits that, along the centuries, have lead to more and more engaging scientific discoveries in more and more far away lands, ending only in the twentieth century with the complete mapping of all the continents. Nuclear Physics is living an analogous adventure on the plane of contrast... - Italian: Se lo stato attuale delle conoscenze teoriche e sperimentali della Fisica Nucleare si potesse ridurre a una carta geografica o un mappamondo, allora la nostra epoca si potrebbe paragonare per certi versi alla fine del Medioevo e per altri al Rinascimento: epoche in cui, accanto alla conoscenza consolidata del Vecchio mondo, ci furono grandi e rivoluzionarie spedizioni come la scoperta dell'America o il periplo del Capo di Buona Speranza, esplorazioni geografiche volte al raggiungimento dei limiti che, nel corso dei secoli, hanno portato a scoperte scientifiche sempre più avvincenti in terre sempre più lontane, culminate solo nel ventesimo secolo con la completa mappatura di tutte le terre emerse. La Fisica Nucleare sta vivendo un'avventura analoga sul piano della contrapposizione tra la conoscenza acquisita sui nuclei stabili e la scoperta delle sorprendenti proprietà esotiche dei nuclei instabili, più difficili da produrre, da studiare e da comprendere.

physics.pop-ph↗

arXiv2011

How does a drinking straw balance work?

We examine working mechanism of a drinking straw balance. Unlike the usual horizontal level balances which rely on the pivotal rotation, a drinking straw balance shows rolling motion. Because of this rolling and relative position between the pin and the center line of a straw, a new equilibrium state is possible after placement of a test mass. Relative errors between the measured values by a drinking straw balance and an electronic scale are order of 22%. Minimum value of a measurable mass by a straw balance is order of 10 mg.

physics.pop-ph↗

arXiv2011

The role of the virtual work in Faraday's law

In the context of Faraday's induction law, we show that the concept of virtual work provides another point of view to clarify the nature of the induced electric field, as well as the fact that the integral over a closed path of the induced electric field is not the work performed by a unit charge. The usefulness of the concept of virtual conservativity is discussed. Further, we study the relation between the electromotive force and the real work done by an external agent to keep a circuit at constant velocity. From this discussion it is observed that magnetic forces can be non-conservative from the mathematical point of view, but can be treated as conservative for all practical purposes.

physics.class-ph↗

arXiv2011

Mystery of the Cosmological Constant

The 2011 Nobel prize in physics has been awarded to S. Perlmutter, A. Riess and B. Schmidt for their path breaking discovery that the rate of expansion of the universe is increasing with time. The trio used Type Ia supernovae (SNe Ia) as standard candles to estimate their luminosity-distances. To appreciate some of the far reaching implications of their work, I have provided an elementary exposition of general theory of relativity, accelerated expansion of the universe, luminosity-distance, SNe Ia and the cosmological constant problem.

physics.pop-ph↗

arXiv2011

Partition function of 1-, 2-, and 3-D monatomic ideal gas: A simple and comprehensive review

This article discusses partition function of monatomic ideal gas which is given in Statistical Physisc at Physics Department, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Indonesia. Students in general are not familiar with partition function. This unfamiliarness was detected at a problem of partition function which was re-given in an examination in other dimensions that had been previously given in the lecture. Based on this observation, the need of a simple but comprehensive article about partition function in one-, two-, and three-dimensions is a must. For simplicity, a monatomic ideal gas is chosen.

physics.pop-ph↗

arXiv2011

Abstract art grandmasters score like class D amateurs

Hawley-Dolan and Winner had asked the art students to compare paintings by abstract artists with paintings made by a child or by an animal. In 67% of the cases, art students said that the painting by a renowned artist is better. I compare this with the winning probability of the chessplayers of different ratings. I conclude that the great artists score on the level of class D amateurs.

physics.pop-ph↗