Ancient and modern rangefinders
Rangefinders are instruments used for ballistics and for surveying in general. Here a short discussion of some of them, ranging from the ancient Rome to the modern methods.
physics.pop-ph↗
arXiv subjects
Amelia Carolina Sparavigna
Publications and source records attributed to Amelia Carolina Sparavigna.
An Etruscan Dodecahedron
The paper is proposing a short discussion on the ancient knowledge of Platonic solids, in particular, by Italic people.
math.HO↗
A Roman Dodecahedron for measuring distance
Here I am discussing a possible use of a Roman Dodecahedron, a bronze artifact of gallo-roman origin, for measuring distance. A dodecahedron, found at Jublains, the ancient Nouiodunum, dating from the 2nd or 3rd century AD, is used to create a model. Looking through the model, it is possible to test it for measurements of distance based on similar triangles.
physics.pop-ph↗
Hemaka's constant
As proposed in a previous paper, the decorations of ancient objects can provide some information on the approximate evaluations of constant π, the ratio of circumference to diameter. Here we discuss some disks found in the tomb of Hemaka, the chancellor of a king of the First Dynasty of Egypt, about 3000 BC. The discussion is based on measurements of the dimensionless ratio of lengths.
physics.pop-ph↗
Number pi from the decoration of the Langstrup plate
Studies of ancient bronze artifacts can be useful in understanding the progression of human knowledge of mathematics and geometry. Here I discuss the decoration composed by several circles and spirals of the Langstrup belt disk, an artifact of the Bronze Age found in Denmark. I am showing by measurements of diameters and distances of spirals, that the artist who made the decoration knew some approximations by rational numbers of the number pi, the dimensionless physical quantity representing the ratio of circumference to diameter.
physics.pop-ph↗
Ancient bronze disks, decorations and calendars
Recently, it was published that some ancient bronze disks could had been calendars, that is, that their decorations had this function. Here I am discussing an example, the disk of the Trundholm Sun Chariot, proposing a new interpretation of it, giving a calendar of 360 days. Some geometric diagrams concerning the decoration layout are also proposed.
physics.pop-ph↗
Internal waves and vortices in satellite images
Some recent papers proposed the use of the satellite images of Google Earth in teaching physics, in particular to see some behaviours of waves. Reflection, refraction, diffraction and interference are easy to be found in these satellite maps. Besides Google Earth, other sites exist, such as Earth Observatory or Earth Snapshot, suitable for illustrating the large-scale phenomena in atmosphere and oceans In this paper, we will see some examples for teaching surface and internal sea waves, and internal waves and the Kármán vortices in the atmosphere. Aim of this proposal is attracting the interest of students of engineering schools to the physics of waves.
physics.pop-ph↗
Measuring the thermal diffusivity in a student laboratory
The paper describes a method for measuring the thermal diffusivity of materials having a high thermal conductivity. The apparatus is rather simple and low-cost, being therefore suitable in a laboratory for undergraduate students of engineering schools, where several set-ups are often required. A recurrence numerical approach solves the thermal field in the specimen, which is depending on the thermal diffusivity of its material. The numerical method requires the temperature data from two different positions in the specimen, measured by two thermocouples connected to a temperature logger.
physics.ed-ph↗
Measuring times to determine positions
Among the first devices used to measure the time we find the sundials and the water-clocks, as told by Vitruvius in his book on the Architecture. The sundials work because of the shadows cast by a rod or pole, the gnomon, on their basements. Besides being an instrument able to measure the time intervals, the sundial provided information on Earth and heaven to the ancient astronomers. Here we discuss how this device is able to determine the latitude and the north-south direction. The problem of the longitude is also shortly discussed.
physics.pop-ph↗
Two amateur astronomers at Berkeley
The book on Mechanics of the Physics at Berkeley, by C. Kittel, W.D. Knight and M.A. Ruderman, is proposing at the end of its first chapter some problems of simple astronomy within the solar system. The discussion begins with two amateur astronomers who set for themselves the goal of determining the diameter and mass of the Sun. Here we discuss the problems proposed by the book and some other matters on ancient and modern astronomical studies of the solar system.
physics.pop-ph↗
Cooking the volumes
Cooking possesses a system of units of measurement, that includes measures of volumes based on pre-metric units. This paper discusses the cooking measures and compares their features with those of the ancient Roman measures of capacity.
physics.pop-ph↗
Variations of images to increase their visibility
The calculus of variations applied to the image processing requires some numerical models able to perform the variations of images and the extremization of appropriate actions. To produce the variations of images, there are several possibilities based on the brightness maps. Before a numerical model, I propose an experimental approach, based on a tool of Gimp, GNU Image Manipulation Program, in order to visualize how the image variations can be. After the discussion of this tool, which is able to strongly increase the visibility of images, the variations and a possible functional for the visibility are proposed in the framework of a numerical model. The visibility functional is analogous to the fringe visibility of the optical interference.
cs.CV↗
Moving sand dunes
In several desert areas, the slow motion of sand dunes can be a challenge for modern human activities and a threat for the survival of ancient places or archaeological sites. However, several methods exist for surveying the dune fields and estimate their migration rate. Among these methods, the use of satellite images, in particular of those freely available on the World Wide Web, is a convenient resource for the planning of future human settlements and activities.
physics.geo-ph↗
An image processing of a Raphael's portrait of Leonardo
In one of his paintings, the School of Athens, Raphael is depicting Leonardo da Vinci as the philosopher Plato. Some image processing tools can help us in comparing this portrait with two Leonardo's portraits, considered as self-portraits.
cs.CV↗
A self-portrait of young Leonardo
One of the most famous drawings by Leonardo da Vinci is a self-portrait in red chalk, where he looks quite old. In fact, there is a sketch in one of his notebooks, partially covered by written notes, that can be a self-portrait of the artist when he was young. The use of image processing, to remove the handwritten text and improve the image, allows a comparison of the two portraits.
cs.CV↗
Chersiphron & Son Engineers
An ancient engineering firm worked successfully in the construction of one of the Seven Wonders of the Ancient World. The engineers used inclined planes, bags of sand and shafts of columns and architraves as wheels and axels.
physics.pop-ph↗
Ancient concrete works
It is commonly believed that the ancient Romans were the first to create and use concrete. This is not true, as we can easily learn from the Latin literature itself. For sure, Romans were able to prepare high-quality hydraulic cements, comparable with the modern Portland cements. In this paper, we will see that the use of concrete is quite older, ranging back to the Homeric times. For instance, it was used for the floors of some courts and galleries of the Mycenaean palace at Tiryns
physics.pop-ph↗
Fairy chimneys in Peru
Erosion creates beautiful landscapes. In most cases, it is just the local population to know them. Google Maps can be helpful for locating the places, for their studies and eventual projects of preservation. An interesting example is given by a landscape of fairy chimneys in Peru, near Pampachiri and San Pedro de Larcay. It is remarkable the fact that some of them have been adapted as dwelling places.
physics.geo-ph↗