With False Friends Like These, Who Can Notice Mistakes?

Adversarial examples crafted by an explicit adversary have attracted significant attention in machine learning. However, the security risk posed by a potential false friend has been largely overlooked. In this paper, we unveil the threat of hypocritical examples -- inputs that are originally misclassified yet perturbed by a false friend to force correct predictions. While such perturbed examples seem harmless, we point out for the first time that they could be maliciously used to conceal the mistakes of a substandard (i.e., not as good as required) model during an evaluation. Once a deployer trusts the hypocritical performance and applies the "well-performed" model in real-world applications, unexpected failures may happen even in benign environments. More seriously, this security risk seems to be pervasive: we find that many types of substandard models are vulnerable to hypocritical examples across multiple datasets. Furthermore, we provide the first attempt to characterize the threat with a metric called hypocritical risk and try to circumvent it via several countermeasures. Results demonstrate the effectiveness of the countermeasures, while the risk remains non-negligible even after adaptive robust training.Comment: AAAI 202

Die analyse eines mathematischen Modells und der Regressionsgleichung für die berechnung inerziäller Parameter von Körperteilen in jungen Chinesinnen

Objective: In this study a mathematical model was set up for calculating the inertial parameters of body segments in young Chinese female students. Methods: On the sample of 50 young Chinese women the inertial parameters, mass and mass center of body segments, were determined by using the Computed Tomography – Digital Image Processing (CT-DIP) method. Results: A 16-segment mathematical model of young Chinese women was set up and a binary regression equation for inertial parameters of body segments calculation was established, in which body weight and stature were treated as independent variables. Conclusion: The study provided a method for a simple calculation of mass, mass centre and moment of inertia both of the segments and of the total body in the population of young Chinese womenUvod Od samih početaka proučavanja čovječjeg kretanja, koncept fizikalnog modeliranja tijela bio je imanentan tim istraživanjima. Braune i Fischer, Hanavan, Hatze, Delp – autori su koji su obilježili razvoj modeliranja ljudskog tijela s primjenama u kineziologiji. Ovaj rad temelji se na pristupu Millerove i Nelsona, odnosno Zatsiorskyog i Seluyanova. Cilj je bio odrediti i analizirati inercijske podatke tijela mladih kineskih žena. Metode Uzorak je obuhvatio 50 žena, studentica, u dobi od 18 do 23 godine. Uporabljena je metoda Computed Tomography – Digital Image Processing (CT-DIP) za analizu 16 segmenata tijela. Na temelju razine sive boje i gustoće svake strukture i tkiva u slikama tih segmenata, inercijski parametri segmenata izracunati su metodom konačnih jedinica. Na kraju su procijenjeni masa, središte mase i moment inercije segmenta. Matematički model je opisan kao n-segmentni sustav s više stupnjeva slobode na spojevima segmenata. To je sustav sastavljen od niza pretpostavljeno homogenih krutih tijela jednostavnih geometrijskih oblika koji su spojeni u zglobovima, a na temelju Hanavanova koncepta 16-segmentnog sustava. Utvrđena je binarna regresijska jednadžba kojom se može izračunati masa, središte mase i moment inercije tjelesnih segmenata. Tjelesna masa i visina korištene su kao nezavisne varijable. Rezultati Prikazani su prosječni podaci za masu, središte mase i moment inercije segmenta i cijelog tijela izračunati metodom CT-DIP. Prikazani su kompletni rezultati dizajna 16- segmentnog modela tijela i inercijalni parametri izračunati binarnom regresijskom jednadžbom. Rasprava Uporabom balansne ploče i metode CT-DIP određeni su i uspoređeni inercijski podaci tijela. Pored standardnih nalaza, autori konstatiraju da ovakav pristup odražava različite karakteristike različitih ljudskih rasa. U okviru evaluacije binarne regresijske jednadžbe najveće diskrepancije u rezultatima pojavile su se u rezultatima za šake i stopala. Međutim, te diskrepancije nisu ozbiljnije utjecale na izračune jer su njihovi momenti bili izuzetno maleni u usporedbi s onima ostalih segmenata. U usporedbi izračunatih vrijednosti i onih dobivenih na balansnoj platformi najveća apsolutna varijanca mase cijeloga tijela iznosila je 3.01 kg, najveća relativna varijacija 3.88%, najveća apsolutna varijanca središta mase cijelog tijela 3.78 cm i najveća relativna varijacija 3.75%. Zaključak Provedena studija pokazala je da je pristup matematičkim modeliranjem dobro prilagođen populaciji mladih kineskih žena. Binarna regresijska jednadžba pokazala se jednostavnim, a vrijednim sredstvom u primjeni tog postupka. Potrebna su daljnja istraživanja da bi se povećala pouzdanost zaključaka.Ziel: In dieser Studie wurde ein mathematisches Modell für die Berechunng inerziäller Parameter von Hörperteilen in jungen Chinesinnen gestaltet. Methoden: Inerziälle Parameter, die Masse und das Massenzentrum von Hörperteilen wurden bei 50 jungen Chinesinnen mittels der Digitalen Bildbearbeitungsmethode (Digital Image Processing – DIP) bestimmt. Ergebnisse: 16-teiliges mathematisches Modell von jungen Chinesinnen wurde gestaltet zusammen mit der binären Regressionsgleichung für die Berechnung von inerziällen Parametern des Hörpergewichts und der Hörperteile. Hörpergewicht und Statur wurden als unabhängige Variablen betrachtet. Schlussfolgerung: Das Resultat dieser Analyse war die Gestaltung einer Methode für die einfache Berechnung von Masse, Massenzentrum und Inerzmoment einzelner Hörperteile und des ganzen Hörpers bei jungen Chinesinnen

Simulation of diffuse reflectance for characterisation of particle suspensions

We employ a physical theory to construct a computational model that accounts for both multiple scattering and absorption of light. The approach does not require a calibration model. Mie theory to describe single particle scattering, which is combined with the diffuse approximation to the radiative transfer equation to provides an analytical prediction of the reflectance. This approach is applied to experimental reflectance measurements on polystyrene particle suspensions with a wide range of particle radii and volume fractions. The method provides good estimates of the suspension properties from a full NIR-vis-UV spectrum