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Heritage ◽  
2022 ◽  
Vol 5 (1) ◽  
pp. 157-169
Author(s):  
Arnd Adje Both

This paper presents the results of a study on the quadruple flutes (multiple pipes) from the UNESCO World Heritage Centre of Teotihuacan, Mexico, based on a thorough examination of the fragmented, restored and partly reconstructed archaeological finds and the manufacture and subsequent test of a series of playable reproductions with a refined reconstructive design. For the latter, organological features, such as the diameter, number and position of the fingerholes/tone holes and the length of the individual pipes of the restored finds are challenged and a new design is proposed that might be closer to the original construction of the Teotihuacan instruments. The study reveals a better understanding of the particular construction, acoustics and musical possibilities of the Teotihuacan quadruple flutes.


2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Matthew Steinberg ◽  
Javier Prior

AbstractHyperinvariant tensor networks (hyMERA) were introduced as a way to combine the successes of perfect tensor networks (HaPPY) and the multiscale entanglement renormalization ansatz (MERA) in simulations of the AdS/CFT correspondence. Although this new class of tensor network shows much potential for simulating conformal field theories arising from hyperbolic bulk manifolds with quasiperiodic boundaries, many issues are unresolved. In this manuscript we analyze the challenges related to optimizing tensors in a hyMERA with respect to some quasiperiodic critical spin chain, and compare with standard approaches in MERA. Additionally, we show two new sets of tensor decompositions which exhibit different properties from the original construction, implying that the multitensor constraints are neither unique, nor difficult to find, and that a generalization of the analytical tensor forms used up until now may exist. Lastly, we perform randomized trials using a descending superoperator with several of the investigated tensor decompositions, and find that the constraints imposed on the spectra of local descending superoperators in hyMERA are compatible with the operator spectra of several minimial model CFTs.


Author(s):  
Abdul Qadir Bhatti ◽  
◽  
Abdul Wahab ◽  
Wadea Sindi ◽  
◽  
...  

Laser scanning is a fast-developing technology, which collects millions of points and creates a framework within a few minutes, generating a 'point cloud' of the structure. Laser scanning is a quite new but rapidly evolving technology that has been reviewed. this research study has used most modern models of laser scanners and their accompanying software that are capable of accurate capture and alignment of point clouds. Consequently, the laser scans have precisely captured the current geometry of each structure, which is irregular in many cases due to inherently complex geometry, anomalies during the original construction, aging, deterioration, and structural damage. As both the exterior and interior of the structure have been scanned, the point cloud became a digital 3D image of the historical building, which can be virtually toured from inside and outside. A 4-story public building was scanned using a 3D laser scanner to determine the architectural and structural drawings of the response to an earthquake. The application of passive control using a damper with the laser scanner has been modelled in this study. The results corroborate that this technique provides the best outcomes for reducing seismic damage collapses.


2021 ◽  
Author(s):  
Matthew Steinberg ◽  
Javier Prior

Abstract Hyperinvariant tensor networks (hyMERA) were introduced as a way to combine the successes of perfect tensor networks (HaPPY) and the multiscale entanglement renormalization ansatz (MERA) in simulations of the AdS/CFT correspondence. Although this new class of network shows much potential for simulating conformal field theories on hyperbolic bulk manifolds with quasiperiodic boundaries, many issues must still be solved. In this manuscript we analyze the challenges related to optimizing tensors in a hyMERA with respect to some critical spin chain, and compare with standard approaches in MERA. Additionally, we show two new sets of tensor decompositions which exhibit different properties from the original construction, and imply that the multitensor constraints are more general than previously suggested. Lastly, we provide numerical evidence that the constraints imposed on the spectra of local descending superoperators in hyMERA are compatible with the operator spectra for many minimial model CFTs.


Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3509
Author(s):  
Michał Makowski ◽  
Lech Knap

In this work an original construction of a vibration damper controlled by means of a valve with a short time of operation lag is presented. The valve-controlling properties of the damper regulates the flow of fluid between the chambers of the damper and was constructed using piezoelectric actuators, whose characteristic feature is the possibility to change dimensions, e.g., length, under the influence of voltage. As a result, by changing voltage it is possible to control the throttle of the flow by changing the width of a gap, which influences a change of damping forces. Such a solution enables a quicker change of damping forces than in other kinds of controlled damper. Due to the obtained properties, the damper may be applied to reduce the vibrations of vehicles and machines that undergo quick-change loads. In the article, the results of experimental studies of the aforementioned damper are presented. Based on the results, dissipative characteristics were determined. Also, results of numerical studies comprising the development of a numerical model of a controlled piezoelectric damper are shown. Results of numerical studies, as well as experimental studies, are presented in the form of dissipative characteristics. Comparison of results of numerical and experimental studies confirms the possibility to apply this kind of construction in semi-active systems of vibration reduction of vehicles and machines.


2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Yi-Fong Lin

A famous paper that has been cited more than four hundred times tried to combine (a) the preference ranking organization method for enrichment evaluations (PROMETHEE) and (b) the analytic hierarchy process (AHP) to construct a new method for multicriteria decision-making problems. The paper developed a consistent comparison matrix for their AHP by the defined first row and then they allowed the expert to change several entries in the comparison matrix. Hence, how to construct a new comparison matrix that is (i) consistent and (ii) satisfying the assigned values by the expert becomes a challenging problem. A recent article provided a reply to the above problem by the construction of all entries for the comparison matrix. However, they did not follow the original design proposed by the famous paper. In this paper, we present a new approach with a proposition that satisfies the original design of the famous paper and also achieves two goals (i) and (ii). The research gap of proof is fulfilled by this paper. Our findings explain that the original construction of the famous paper to develop a consistent comparison matrix only by the first row with several assigned values by an expert is indeed workable under two additional restrictions proposed by the recent article. We believe that after our proposition, researchers have the confidence to execute the original design of the paper that has been cited more than four hundred times.


Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 244
Author(s):  
Jakub Sandak ◽  
Anna Sandak ◽  
Lea Legan ◽  
Klara Retko ◽  
Maša Kavčič ◽  
...  

Advanced imaging techniques can noninvasively characterise, monitor, and evaluate how conservation treatments affect cultural heritage objects. In this specific field, hyperspectral imaging allows nondestructive characterisation of materials by identifying and characterising colouring agents, binders, and protective coatings as components of an object’s original construction or later historic additions. Furthermore, hyperspectral imaging can be used to monitor deterioration or changes caused by environmental conditions. This paper examines the potential of hyperspectral imaging (HSI) for the evaluation of heritage objects. Four cameras operating in different spectral ranges were used to nondestructively scan a beehive panel painting that originated from the Slovene Ethnographic Museum collection. The specific objective of this research was to identify pigments and binders present in the samples and to spatially map the presence of these across the surface of the art piece. Merging the results with databases created in parallel using other reference methods allows for the identification of materials originally used by the artist on the panel. Later interventions to the original paintings can also be traced as part of past conservation campaigns.


2021 ◽  
Vol 127 (1) ◽  
pp. 131-160
Author(s):  
Leonel Robert ◽  
Luis Santiago

We revise the construction of the augmented Cuntz semigroup functor used by the first author to classify inductive limits of $1$-dimensional noncommutative CW complexes. The original construction has good functorial properties when restricted to the class of C*-algebras of stable rank one. The construction proposed here has good properties for all C*-algebras: we show that the augmented Cuntz semigroup is a stable, continuous, split exact functor, from the category of C*-algebras to the category of Cu-semigroups.


Author(s):  
Laurel Bestock

In the early part of the 2nd millennium bce, the Egyptian state took control of Lower Nubia, building a series of monumental fortresses along the Nile that are remarkable for their sophisticated military architecture. This was Egypt’s first major expansion beyond its traditional borders. Various theoretical models of imperialism and core-periphery interactions have been brought to bear on studies of the forts and their populations, seeking to explain the military, economic, and ideological purposes behind the original construction of the monuments as well as the apparently shifting nature of their occupation, from probable rotating garrisons to more permanent settlement, and their interactions with local populations (cf. Trigger 1976:64–81; Adams 1977:183–88; Zibelius-Chen 1988:69–135; S.T. Smith 1995, 2003; Williams 1999; Flammini 2008; Török 2009:79–101; Vogel 2004; Knoblauch 2008). The resulting picture of Egyptian occupation of Nubia is a nuanced if not entirely agreed upon one. The fortresses are important to archaeology more broadly because they offer a richly documented case study for consideration of state control of foreign territory; they belong in the broader discourse about imperialism, colonization, and colonialism, how different state strategies of control can be understood in the material record, and how people live and interact in border zones. That the methods of Middle Kingdom control can be contrasted to both earlier and later Egyptian strategies of interaction with Nubia, and that the region is one of modern colonial entanglements, makes a critical approach to its occupation in the Middle Kingdom all the more vital.


Author(s):  
Aleksandr Yu. Aleksandrov ◽  
◽  
Natalya R. Andriyanova ◽  
Aleksey A. Tikhonov ◽  
◽  
...  

A dynamically symmetric satellite in a circular orbit of small inclination is considered. The problem of the Lorentzian stabilization of the satellite in the orbital coordinate system in the indirect equilibrium position is solved under the conditions of the perturbing effect of the gravitational torque. To solve this problem, which is characterized by incomplete control, a method of averaging differential equations is developed. Using the original construction of the unsteady Lyapunov function, we obtain sufficient conditions for the asymptotic stability of the programmed satellite motion mode in the form of constructive inequalities with respect to the control parameters.


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