Quasistatic cavity resonance

Nowadays our life continuously connects various kinds of gadgets. Most of these devices work using an accumulator. But the reserve of energy in batteries is emptying very fast. We need to charge the battery over and over again for using gadgets to continue our work

Oculus Rift

Nowadays our world is closely connected with technologies. Changes come in people's lives with technology. People invent new gadgets, tools, machines and more useful things every day. As a rule, all these inventions make our life better and easier

ControlFreak: Signature Chaining to Counter Control Flow Attacks

Abstract: Many modern embedded systems use networks to communicate. This increases the attack surface: the adversary does not need to have physical access to the system and can launch remote attacks. By exploiting software bugs, the attacker might be able to change the behavior of a program. Security violations in safety-critical systems are particularly dangerous since they might lead to catastrophic results. Hence, safety-critical software requires additional protection. We present an approach to detect and prevent control flow attacks. Such attacks maliciously modify program's control flow to achieve the desired behavior. We develop ControlFreak, a hardware watchdog to monitor program execution and to prevent illegal control flow transitions. The watchdog employs chained signatures to detect any modification of the instruction stream and any illegal jump in the program even if signatures are maliciously modified

Usvajanje glasovnih promjena u predškolske djece

Razvoj govora složeni je proces koji počinje od prenatalnog razdoblja djeteta do njegovog polaska u školu. Djetetova okolina utječe na njegov razvoj, pa tako i na razvoj njegova govora, zbog čega je važno da dijete ima poticaj okoline od prvog glasanja, tj. gugutanja. Dijete kroz razvoj postepeno usvaja morfološke, fonološke i fonetske procese, a prije polaska u školu dijete urednog razvoja ima gramatičan govor. Ovim radom istražio se jedan dio usvajanja govora, a to je usvajanje glasovnih promjena u predškolske djece. Za potrebe rada provelo se istraživanje sa 30 djece u dobi od tri do šest godina u zagrebačkom vrtiću Cvrčak. Djecu se pomoću igre memory poticalo da izgovaraju riječi u kojima se treba provesti glasovna promjena, a rezultati su zabilježeni audio snimkom. Glasovne promjene koje su se ispitivale jesu: nepostojano a, jednačenje po mjestu tvorbe, jednačenje po zvučnosti, sibilarizacija i palatalizacija. Preslušavanjem i analiziranjem rezultata pokazano je da djeca glasovne promjene usvajaju u šestoj godini života, a najlakše provode glasovne promjene nepostojano a i jednačenje po zvučnosti, dok najteže provode palatalizaciju.Speech acquisition is a complex process that starts form the prenatal child development up to the child's start of school. A child’s environment influences all of its development including speech, which is why a child should be stimulated from its first vocalization, cooing. Through its development, the child gradually adopts morphological, phonological and phonetic processes and by the time a typically developed child starts school it should have adopted all pronunciations and a grammatically correct speech. This study has explored a part of speech acquisition, specifically acquisition of sound changes in preschool children. For this purpose a research with 30 participants aged four to six was conducted in Zagreb’s kindergarten Cvrčak. The children were stimulated by means of a memory game to pronounce a word that is supposed to have a sound change and the results were audio recorded. Voice changes that were being examined were: movable a, coarticulation, voicing assimilation, assibilation and palatalization. Subsequent analyses of these recordings have shown that children acquire the use of sound changes at six years of age, while acquiring the sound change movable a and voicing assimilation with the most ease, while they acquire the sound change palatalization with the most difficulties

La actitud de los profesores croatas de español como lengua extranjera hacia la corrección de los errores en la expresión oral

Ispravljanje pogrešaka sastavni je dio svakog nastavnog procesa i kao takvo uvelike utječe na učenika, zbog čega je važno da svaki nastavnik zna i može odrediti kada, kako i što ispravljati. Pogreška se definira kao odstupanje od pravila ciljnog jezika, a sa stajališta profesora učenička pogreška je bilo kakva njegova reakcija na učenikovu izjavu koju on opovrgava, koju mora preoblikovati ili zatražiti njezin ispravak. Ovim radom željeli su se istražiti stavovi profesora prema ispravljanju učeničkih usmenih pogrešaka. U prvom, teorijskom dijelu objasnilo se kako se razvijalo poimanje i ispravljanje pogrešaka kroz povijest usvajanja jezika. Također, predstavile su se vrste pogrešaka te način i tehnike ispravljanja pogrešaka. U drugom dijelu predstavilo se istraživanje koje se provelo među hrvatskim profesorima španjolskog kao stranog jezika o njihovim stavovima vezanim za ispravljanje pogrešaka u usmenom izražavanju.La corrección de errores es parte integral de la enseñanza de lenguas extranjeras y como tal afecta mucho a los estudiantes, por lo que es importante que cada profesor sepa y pueda determinar cuándo y cómo corregir. El error se define como una desviación de las reglas de la lengua meta y desde el punto de vista del profesor es cualquier tipo de reacción que, ante una elocución del alumno, debe transformar, desaprobar o pedir una mejora. Con este trabajo se pretende estudiar la actitud de los profesores croatas hacia la corrección de los errores en la expresión oral. En la primera parte teórica se explica cómo se desarrolló la percepción del error durante la historia de enseñanza de lenguas. Además, se presentan los tipos de errores y técnicas de corrección. En la segunda parte, se expone la investigación hecha entre los profesores croatas de español como lengua extranjera sobre sus actitudes con respecto a la corrección de errores en la expresión oral

Glimmers: Resolving the Privacy/Trust Quagmire

Many successful services rely on trustworthy contributions from users. To establish that trust, such services often require access to privacy-sensitive information from users, thus creating a conflict between privacy and trust. Although it is likely impractical to expect both absolute privacy and trustworthiness at the same time, we argue that the current state of things, where individual privacy is usually sacrificed at the altar of trustworthy services, can be improved with a pragmatic $Glimmer$ $of$ $Trust$, which allows services to validate user contributions in a trustworthy way without forfeiting user privacy. We describe how trustworthy hardware such as Intel's SGX can be used client-side -- in contrast to much recent work exploring SGX in cloud services -- to realize the Glimmer architecture, and demonstrate how this realization is able to resolve the tension between privacy and trust in a variety of cases

SGXTuner: Performance Enhancement of Intel SGX Applications via Stochastic Optimization

Intel SGX has started to be widely adopted. Cloud providers (Microsoft Azure, IBM Cloud, Alibaba Cloud) are offering new solutions, implementing data-in-use protection via SGX. A major challenge faced by both academia and industry is providing transparent SGX support to legacy applications. The approach with the highest consensus is linking the target software with SGX-extended libc libraries. Unfortunately, the increased security entails a dramatic performance penalty, which is mainly due to the intrinsic overhead of context switches, and the limited size of protected memory. Performance optimization is non-trivial since it depends on key parameters whose manual tuning is a very long process. We present the architecture of an automated tool, called SGXTuner, which is able to find the best setting of SGX-extended libc library parameters, by iteratively adjusting such parameters based on continuous monitoring of performance data. The tool is to a large extent algorithm agnostic. We decided to base the current implementation on a particular type of stochastic optimization algorithm, specifically Simulated Annealing. A massive experimental campaign was conducted on a relevant case study. Three client-server applications Memcached, Redis, and Apache were compiled with SCONE's sgx-musl and tuned for best performance. Results demonstrate the effectiveness of SGXTuner

Correction due to finite speed of light in absolute gravimeters

Correction due to finite speed of light is among the most inconsistent ones in absolute gravimetry. Formulas reported by different authors yield corrections scattered up to 8 $\mu$Gal with no obvious reasons. The problem, though noted before, has never been studied, and nowadays the correction is rather postulated than rigorously proven. In this paper we make an attempt to revise the subject. Like other authors, we use physical models based on signal delays and the Doppler effect, however, in implementing the models we additionally introduce two scales of time associated with moving and resting reflectors, derive a set of rules to switch between the scales, and establish the equivalence of trajectory distortions as obtained from either time delay or distance progression. The obtained results enabled us to produce accurate correction formulas for different types of instruments, and to explain the differences in the results obtained by other authors. We found that the correction derived from the Doppler effect is accountable only for $\frac23$ of the total correction due to finite speed of light, if no signal delays are considered. Another major source of inconsistency was found in the tacit use of simplified trajectory models

Lattices of topologies of algebraic systems

The article is based on the report, which was delivered on a plenary sitting on the 5th International Algebraic Conference in the Ukraine (Odessa, July, 2005) and is a survey of the results on the lattices of topologies of different algebraic systems