Experimental investigation of omnidirectional multiphysics bilayer invisibility cloak with anisotropic geometry

Thermal-electric bilayer invisibility cloak can prevent the heat flux and electric current from touching the object without distorting the external temperature and electric potential fields simultaneously.In this paper,we design an omnidirectional thermal-electric invisibility cloak with anisotropic geometry.Based on the theory of neutral inclusion,the anisotropic effective thermal and electric conductivities of confocal elliptical bilayer core-shell structure are derived,thus obtaining the anisotropic matrix material to eliminate the external disturbances omnidirectionally.The inner shell of the cloak is selected as an insulating material to shield the heat flux and electric current.Then,the omnidirectional thermal-electric cloaking effect is verified numerically and experimentally based on the theoretical anisotropic matrix and manufactured composite structure,respectively.Furthermore,we achieve the thermal-electric cloaking effect under a specific direction of heat flux and electric current using the isotropic natural materials to broaden the selection range of materials.The method proposed to eliminate anisotropy and achieve the omnidirectional effect could also be expanded to other different physical fields for the metadevices with different functions.

Commodity Value Theory-Invisible Hands Seen

Through the revelation of“commodity value”,the“invisible hand”described by Adam Smith is now clearly visible.It is precisely“commodity value”that guides people to seek benefits for themselves and for others,adding enormous wealth to society.

LG Invision

在手机移动电视技术非常成熟的美国,手机具备移动电视功能是件非常普通的事,为此美国通信运营商AT＆T也没少花功夫进行推广。近日,为了让旗下定制的移动电视手机种类更加丰富。AT＆T再次携手LG全新推出了—散Invision移动电视手机。

Efficacy of invisible advancement correction for mandibular retraction in adolescents based on Pancherz analysis

BACKGROUND Mandibular retraction is the main etiological mechanism of class II malocclusion in China and the subsequent distal molar relationship can cause functional discomfort in mastication,breathing and the temporomandibular joint.The use of mandibular advancement(MA)devices has recently emerged as an adolescent mandibular retraction treatment;however,current studies regarding the effect thereof are relatively few,and there is lack of sufficient clinical support.AIM To investigate the clinical effect of invisalign MA on the treatment of mandibular retraction in adolescents.METHODS This study included 30 adolescent patients who underwent treatment with the MA appliances from December 2017 to June 2021.The lateral cephalometric data before and after treatment were collected and imported into Dolphin Imaging software.The changes were measured by linear measurement superimposed with lateral cephalometric trajectory based on the Pancherz technology.RESULTS There was no significant difference in the length and position of maxilla before and after the treatment.The position of the mandible moved 3.13 mm,the length increased 4.14 mm,the mandibular ramus length increased 4.09 mm,the body length increased 4.25 mm,and the position of the condyle moved 1.03 mm forward after treatment.Additionally,changes in the incisor sagittal position and labial inclination were observed.The position of the upper incisor point moved back 1.33 mm,without statistical difference,the inclination and tooth angle decreased by 3.44°and 4.06°,respectively;the position of the lower incisor point was moved 2.98 mm,and the inclination and tooth angle increased by 2.62°and 1.23°,respectively.Furthermore,changes in the incisor overjet and molar relationship were seen.Overjet decreased by 4.31 mm,of which 1.78 mm was due to dental factors,accounting for 41.3%of the effect as opposed to 58.7%due to skeletal factors.Molar relationship improved 3.87 mm,with 1.34 mm due to dental factors,and dental and skeletal factors were accounted for 34.6%and 65.4%of the effect,respectively.CONCLUSION For adolescent patients with mandible retraction,invisalign MA can effectively promote the mandible growth,and it was proven to be mainly due to skeletal effects.

Hybrid treatment of varied orthodontic appliances for a patient with skeletal class II and temporomandibular joint disorders:A case report and review of literature

BACKGROUND The relation between orthodontic treatment and temporomandibular disorders(TMDs)is under debate;the management of TMD during orthodontic treatment has always been a challenge.If TMD symptoms occur during orthodontic treatment,an immediate pause of orthodontic adjustments is recommended;the treatment can resume when the symptoms are managed and stabilized.CASE SUMMARY This case report presents a patient(26-year-old,female)with angle class I,skeletal class II and TMDs.The treatment was a hybrid of clear aligners,fixed appliances and temporary anchorage devices(TADs).After 3 mo resting and treatment on her TMD,the patient’s TMD symptom alleviated,but her anterior occlusion displayed deep overbite.Therefore,the fixed appliances with TAD were used to correct the anterior deep-bite and level maxillary and mandibular deep curves.After the levelling,the patient showed dual bite with centric relation and maximum intercuspation discrepancy on her occlusion.After careful examination of temporomandibular joints(TMJ)position,the stable bite splint and Invisible Mandibular Advancement appliance were used to reconstruct her occlusion.Eventually,the improved facial appearance and relatively stable occlusion were achieved.The 1-year follow-up records showed there was no obvious change in TMJ morphology,and her occlusion was stable.CONCLUSION TMD screening and monitoring is of great clinical importance in the TMD susceptible patients.Hybrid treatment with clear aligners and fixed appliances and TADs is an effective treatment modality for the complex cases.

Invisible Web研究综述

本文对有关 Invisible Web的内容进行了全面、详细地介绍。首先论述了什么是 Invisible Web以及为什么要研究 Invisible Web,同时介绍了两个相关概念 ;其次对 Invisible Web不可见的原因加以分析 ;对 Invisible Web的类型进行了划分 ;介绍了 Invisible Web的检索工具 ;最后总结了 Invisible Web研究的方向。

invisible hand 小议

invisible hand 是由英国人亚当·斯密(Adam Smith)首先提出来的。Adam Smith(1723—1790)是英国苏格兰人,经济学家与哲学家。他于1776年完成了经济学史上的经典著作《国富论》(The Wealth of Na-

Individual Identity and Collective Identity in Ralph Ellison's Invisible Man

Ralph Ellison’s Invisible Man deals with the identity issue fundamental for black Americans to reestablish themselves in the white-dominated society.While the narrator suffers from identity crisis in multiples ways,the paper focuses on the conflict between his need to build a distinctive individual identity with the prerequisite to surrender to collective identity in order to blend in the group.

New insights into the extraction of invisible gold in a low-grade high-sulfur Carlin-type gold concentrate by bio-pretreatment

To extract gold from a low-grade(13.43 g/t) and high-sulfur(39.94wt% sulfide sulfur) Carlin-type gold concentrate from the Nibao deposit, Guizhou, a bio-pretreatment followed by carbon-in-pulp(CIP) cyanide leaching process was used. Various methods were used to detect the low-grade gold in the concentrate; however, only time-of-flight secondary-ion mass spectrometry(TOF-SIMS) was successful. With bio-pretreatment, the gold recovery rate increased by approximately 70.16% compared with that obtained by direct cyanide leaching of the concentrate. Various attempts were made to increase the final gold recovery rate. However, approximately 20wt% of the gold was non-extractable. To determine the nature of this non-extractable gold, mineralogy liberation analysis(MLA), formation of secondary product during the bio-pretreatment, and the preg-robbing capacity of the carbonaceous matter in the ore were investigated. The results indicated that at least four factors affected the gold recovery rate: gold occurrence, tight junctions of gold-bearing pyrite with gangue minerals, jarosite coating of the ore, and the carbonaceous matter content.

From Savior to Restrictive Mother——Transformation of Mary Rambo in Invisible Man

Invisible Man is Ralph Ellison's most important work,the hero of which is confused by the problem of his identity.This thesis will discuss the transformation of Mary Rambo in the novel.At the beginning,Mary Rambo was a symbol of hope and encouragement for the hero and a kind of salvation and redemption to him both materially and spiritually.But later,she changed from a savior to a restrictive mother.The hero became restive and guilty under her watchful and anxious care.Thus,the hero must escape her in order to continue his search for identity.

Rethinking on Translator's Invisibility and Visibility

Translator’s Invisibility is Lawrence Venuti’s most famous book.In this book we can conclude his translation theory:translators should be invisible(transparent)or visible in his translation.We will analyze in his opinion which kind of translation is perfect to readers,and how should the translator be visible in his translation by comparing the theories of Friedrich Schleiermacher and Norman Shapiro.Finally we can get a good translator should use foreignizing translation in order to be visible in his translation.

The Discussion of Racial Identity of the Protagonist in the Invisible Man from Post-Colonial Perspective

The African-American novel Invisible Man written by Ralph Ellison is about the miserable suffering of black people in the white society.The black people were invisible in the white world.This thesis analyzes this novel from post-colonialism perspective to discuss the process of looking for the racial identity of the protagonist.

Improving the performance of acoustic invisibility with multilayer structure based on scattering analysis

In this paper, acoustic scattering from the system comprised of a cloaked object and the multilayer cloak with only one single pair of isotropic media is analyzed with a recursive numerical method. The designed acoustic parameters of the isotropic cloak media are assumed to be single-negative, and the resulting cloak can reduce acoustic scattering from an acoustic sensor while allowing it to receive external information. Several factors that may influence the performance of the cloak, including the number of layers and the acoustic dissipation of the medium are fully analyzed. Furthermore, the possibility of achieving acoustic invisibility with positive acoustic parameters is proposed by searching the optimum value in the parameter space and minimizing the scattering cross-section.

Design method of reusable reciprocal invisibility and phantom device

Reusable reciprocal invisibility and phantom device is proposed and designed based on multi-folded transformation optics and equivalent components. In comparison with the reported reciprocal invisibility cloaks, the material parameters of the device presented here are homogeneous, and the hiding of the target object does not require any “anti-object” at all,which dramatically breaks through the limitations of the “anti-object” design in previous reciprocal cloak design. Perfectly illusion effect is also found by reasonably setting the material parameters of the restored medium of the device, which can be used to confuse detection radars while hiding target objects. Last but not least, the proposed device has an open structure,which enables the target object enclosed by the device to perform material exchange and simplex transfer of information with the outside world through open channels. In other words, the proposed device has a reusable function, enabling stealth or phantom of new target objects without changing any parameters of the device.

Nonsingularity in two-dimensional cylindrical invisible cloaks

The method of designing electromagnetic invisible cloaks is usually based on the form-invariance of Maxwell＇s equations in coordinate transformation. The exterior boundary of a cylindrical invisible cloak is unchanged and the interior boundary is extended from that of a point to that of a cylindrical region in coordination transformation. This transformation process makes perfect cloaks, but it causes singularity in the constitutive material parameters of cloaks. This singularity makes the cloaks impossible to realize in practice. In order to remove this singularity, this paper sets a small cylindrical region replacing a point in the space transformation. The cylindrical region is so small that it does not affect the invisibility effects, but it can remove the singularity for material parameters. Full wave simulations based on the finite element method were used to verify the designed cloaks.

Invisible anti-cloak with elliptic cross section using phase complement

Based on the theory of phase complement, an anti-cloak with circular cross section can be made invisible to an object outside its domain. As the cloak with elliptic cross section is more effective to make objects invisible than that with circular cross section, a scaled coordinate system is proposed to design equivalent materials of invisible anti- cloak with elliptic cross section using phase complement. The cloaks with conventional dielectric and double negative parameters are both simulated with the geometrical transformations. The results show that the cloak with elliptic cross section through phase complement can effectively hide the outside objects.

Multi-window invisible cloaks

This paper reports that a general method of designing invisible cloaks is using variant constitutive material parameters to realize the space transformation. A hollow region can be hidden after this transformation. It was recently shown （Ma H, Qu S B, Xu Z and Wang J F 2009 Appl. Phys. Lett. 94 103501） that when the original point moves to the boundary of a cloak, the cloak can be designed to be open. Based on this theory, we propose multi-window invisible cloaks which can conceal a group of objects. Full wave simulations for invisible cloaks with regular and irregular shapes verified this method.

Experimental demonstration of an invisible cloak with irregular shape by using tensor transmission line metamaterials

We present the design and the experimental demonstration of an invisible cloak with irregular shape by using tensor transmission line（TL） metamaterials. The fabricated cloak consists of tensor TL unit cells exhibiting anisotropic effective material parameters, while the background medium consists of isotropic TL unit cells. The simulated and the measured field patterns around the cloak show a fairly good agreement, both demonstrate that the fabricated cloak can shield the cloaked interior area from electromagnetic fields without perturbing the external fields. The scattering of the cloaked perfect electric conductor（PEC） is minimized. Furthermore, the nonresonant property of the TL structure results in a relatively broad bandwidth of the realized cloak, which is clearly observed in our experiment.

Design of two-dimensional elliptically cylindrical invisible cloaks with multiple regions

Two-dimensional （2D） elliptically cylindrical invisible cloaks with multiple regions are designed based on the trans-formation optics and the complementary media theory. Multiple invisible cloak regions can be obtained by properly using the compressed or folded transformation in each space layer. The constitutive parameter tensor expressions for each re- gion have been obtained. The results of full wave simulations by using finite element software confirm the validity of the constitutive parameter tensor expressions. In addition, the parameters are relatively easier to realize.

Osteotomy combined with the trephine technique for invisible implant fracture:A case report

BACKGROUND Implant fracture is one of the most serious mechanical complications of dental implants.Conventional treatment necessitates visibility of the apical portion of the fractured implant,whereas for deep and invisible implant fractures,the traditional trephine method has been ineffective.Surgical removal of the marginal bone to expose the fracture surface would be a time-consuming and extensively damaging procedure.Here,we propose a novel technique to address invisible implant fractures.CASE SUMMARY A 50-year-old woman was referred to our department with the chief complaint that her right mandibular implant tooth had fallen out 3 mo earlier.Cone-beam computed tomography examination showed an implant fracture with a fracture surface 5.1 mm below the crestal ridge.The patient was treated with osteotomy combined with the trephine technique to expose the surgical field and remove the implant.The invisible fractured implant was successfully removed,with minimal trauma.A modified Wafer technique-supported guided bone regeneration treatment was then administered to restore the buccal bone wall and preserve the bone mass.Six months later,fine regenerative bone and a wide alveolar crest in the edentulous area were observed,and a new implant was placed.Four months later,restoration was completed using a cemented ceramic prosthesis.Clinical and radiographic examinations 12 mo after loading fulfilled the success criteria.The patient reported no complaints and was satisfied.CONCLUSION Osteotomy combined with the trephine technique can be effectively used to address deep and invisible implant fractures.