AirCode: Unobtrusive Physical Tags for Digital Fabrication

We present AirCode, a technique that allows the user to tag physically fabricated objects with given information. An AirCode tag consists of a group of carefully designed air pockets placed beneath the object surface. These air pockets are easily produced during the fabrication process of the object, without any additional material or postprocessing. Meanwhile, the air pockets affect only the scattering light transport under the surface, and thus are hard to notice to our naked eyes. But, by using a computational imaging method, the tags become detectable. We present a tool that automates the design of air pockets for the user to encode information. AirCode system also allows the user to retrieve the information from captured images via a robust decoding algorithm. We demonstrate our tagging technique with applications for metadata embedding, robotic grasping, as well as conveying object affordances.Comment: ACM UIST 2017 Technical Paper

Image of Veselago lens based upon two-dimensional photonic crystal with triangular lattice

The construction of the multi-focal Veselago lens predicted earlier is proposed on the basis of a uniaxial photonic crystal consisting of cylindrical air holes in silicon that make a triangular lattice in a plane perpendicular to the axis of the crystal. The object and image are in air. The period of the crystal should be $0.44\mu{\rm m}$ to work at the wavelength $1.5\mu{\rm m}$. The lens does not provide superlensing but the half-width of the image is $0.5\lambda$. The lens is shown to have wave guiding properties depending on the substrate material.Comment: 15 pages, 10 figure

Crossing the Line - sustainability and large object conservation in musuems and heritage collections

Large working objects pose significant challenges for the heritage sector. The primary issues are concerned with interpretation, conservation and authenticity but underpinning all of these is the issue of sustainability. Decision making in large object conservation has always revolved around the tension between using it and losing it, or storing it and seeing it decay through neglect. An additional challenge is authenticity. At what point does an object lose its authenticity? How many replacement parts, panels or new paint jobs does it take to reduce an object to a construct? This paper examines these challenges in order to explore a set of ideas that will allow a sustainable approach to large working object conservation in museums and heritage collections to be developed. It will use as a basis for analysis and discussion ground breaking conservation projects at the Fleet Air Arm Museum in Yeovilton in the UK

The stability of an air-maintained cavity behind a stationary object in flowing water

In studies made in the Free Surface Water Tunnel of a projectile running in an air-maintained cavity, the experimental relation between air entrainment rate and cavitation number was determined. The entrainment-rate coefficient CQ = Q/V0d^2, where Q is the air rate in cfs, V0 the free-stream velocity, and d the disk nose diameter, was plotted against cavitation parameter, K = (p0 - pk)/q0 where p0 is the free-stream pressure at the disk center line, pk the cavity pressure, and q0 the free-stream dynamic pressure. This experimental relationship for one single disc is shown for three different velocities in Fig. 1. The curves are similar in shape and each has a minimum value of entrainment coefficient which is designated by CQ^* at a value of K as designated as K^*

Perbandingan penggunaan grid dan teknik celah udara serta pengaruhnya terhadap pengurangan radiasi hambur

Telah dilakukan penelitian perbandingan penggunaan grid dan teknik celah udara serta pengaruhnya terhadap pengurangan radiasi hambur. Penelitian dilakukan dengan menggunakan grid linear yang berbeda rasio, terdiri dari. rasio 6 : 1, 10 : 1 dan 12 :1. Celah udara dibuat dengan mengatur jarak antara obyek dengan film sejauh 30 cm dan dilakukan penyinaran setiap interval 5 cm. Obyek penelitian berupa dua buah koin timbal masing-masing berdiameter 3 cm dan ketebalan 2 mm yang diletakkan dalarn wadah berukuran 22 cm x 16 cm x 18 cm dengan ketinggian air 16 cm. Faktor paparan yang digunakan adalah variasi tegangan tabung dan 50 kV sampai 120 kV dengan kenaikan interval tiap 10 kV, anus tabung 100 mA dan waktu penyinaran 0,40 detik serta jarak fokus ke film 90 cm. Penyinaran dilakukan tanpa grid terlebih dahulu dan hasilnya dibandingkan dengan penyinaran menggunakan grid serta variasi celah udara untuk diketahui tingkat perbaikan kontrasnya. Hasil penelitian menunjukkan bahwa diperoleh kesetaraan densitas dan kontras radiograf antara pemakaian grid rasio 6 1 dengan celah udara 20 cm pada faktor paparan 90 kV 40 mAs dan teknik celah udara 30 cm setara dengan grid rasio 10 : 1 dan 12 : 1 pada faktor paparan 100 kV 40 mAs. It have been done the comparitions experiment of using the grid and the air gap tecnique and the influence to the scatter radiation reducing. This experiment was done with using various linear grid with different ratio, such as 6 : 1, 10 : 1 and 12 : 1 ratio. Using air gap was done with drive the distance between object with interval 5 cm. The experimental object are two Pb coins. They have diameter 3 cm and the thickness 2 mm that put in the plastic box with size 12 cm X 16 cm X 18 cm with water high 16 cm. Exposure factor that using is tube. voltage Variation begin 50 kV till 120 kV, with interval increasing each 10 kV, tube current 100 mA and the exposure time 0,40 second. So, the focus distance to the film 90 cm. Exposure was done without grid first and the result was compare with sliding use grid with air gab variation to know the rate contrast make up. The experiment results show that get the density equelibrium and radiograph density between using grid with ratio 10 : 1 and 12 : 1 with air gap 30 cm at 100 kV 40 mAs and ratio grid 6 : 1 equivalen with air gap 20 cm at 90 kV 40 mAs. The rate magnification image is 1,3 % at the air gap 20 cm and 1,5 % at air gab 30 cm

3-D Object Recognition by the ART-EMAP Evidence Accumulation Network

ART-EMAP synthesizes adaptive resonance theory (AHT) and spatial and temporal evidence integration for dynamic predictive mapping (EMAP). The network extends the capabilities of fuzzy ARTMAP in four incremental stages. Stage I introduces distributed pattern representation at a view category field. Stage 2 adds a decision criterion to the mapping between view and object categories, delaying identification of ambiguous objects when faced with a low confidence prediction. Stage 3 augments the system with a field where evidence accumulates in medium-term memory (MTM). Stage 4 adds an unsupervised learning process to fine-tune performance after the limited initial period of supervised network training. Simulations of the four ART-EMAP stages demonstrate performance on a difficult 3-D object recognition problem.Advanced Research Projects Agency (ONR N00014-92-J-4015); National Science Foundation (IRI-90-00530); Office of Naval Research (N00014-91-J-1309); Air Force Office of Scientific Research (90-0083