Resilience to sensor and actuator attacks is a major concern in the supervisory control of discre... more Resilience to sensor and actuator attacks is a major concern in the supervisory control of discrete events in cyber-physical systems (CPS). In this work, we propose a new framework to design supervisors for CPS under attacks using finite-state transducers (FSTs) to model the effects of the discrete events. FSTs can capture a general class of regular-rewriting attacks in which an attacker can nondeterministically rewrite sensing/actuation events according to a given regular relation. These include common insertion, deletion, event-wise replacement, and finite-memory replay attacks. We propose new theorems and algorithms with polynomial complexity to design resilient supervisors against these attacks. We also develop an open-source tool in Python based on the results and illustrate its applicability through a case study. INDEX TERMS Control system security, cyber-physical systems, formal methods.
Synthesis from linear temporal logic (LTL) specifications provides assured controllers for system... more Synthesis from linear temporal logic (LTL) specifications provides assured controllers for systems operating in stochastic and potentially adversarial environments. Automatic synthesis tools, however, require a model of the environment to construct controllers. In this work, we introduce a model-free reinforcement learning (RL) approach to derive controllers from given LTL specifications even when the environment is completely unknown. We model the problem as a stochastic game (SG) between the controller and the adversarial environment; we then learn optimal control strategies that maximize the probability of satisfying the LTL specifications against the worst-case environment behavior. We first construct a product game using the deterministic parity automaton (DPA) translated from the given LTL specification. By deriving distinct rewards and discount factors from the acceptance condition of the DPA, we reduce the maximization of the worst-case probability of satisfying the LTL specification into the maximization of a discounted reward objective in the product game; this enables the use of model-free RL algorithms to learn an optimal controller strategy. To deal with the common scalability problems when the number of sets defining the acceptance condition of the DPA (usually referred as colors), is large, we propose a lazy color generation method where distinct rewards and discount factors are utilized only when needed, and an approximate method where the controller eventually focuses on only one color. In several case studies, we show that our approach is scalable to a wide range of LTL formulas, significantly outperforming existing methods for learning controllers from LTL specifications in SGs.
OPUS Uluslararası Toplum Araştırmaları Dergisi, 2021
Aletli dalış dünya genelinde pek çok insanın hobi olarak yaptığı aktivite sporlarından birisidir.... more Aletli dalış dünya genelinde pek çok insanın hobi olarak yaptığı aktivite sporlarından birisidir. Geçmişi eski dönemlere kadar gitse de sportif amaçlı yapılan dalışlar son yüzyılda ivme kazanmıştır. Dünya genelinde farklı dalış organizasyonları bu konuda eğitim ve sertifika vermektedirler ve dünyada 6 milyon civarı sertifikalı dalgıç olduğu tahmin edilmektedir. Bu dalgıçların önemli bir kısmı aletli dalış amacıyla dünya genelindeki tanınmış dalış bölgelerine seyahat etmekte, bu sayede gittikleri ülkelerin ekonomisine ciddi katkılarda bulunmaktadırlar. Dünyaca ünlü kayıtlı tanınmış dalış bölgeleri bulunmamakla beraber ülkemiz bu konuda iyi bir potansiyele sahiptir. Buna rağmen ülkemizin bu mevcut potansiyeli yeterince kullanamadığı düşünülmektedir. Bu çalışma dünya genelinde aletli dalış konusunda bazı temel bilgiler ve rakamları sunmanın yanında ülkemizdeki durum hakkında da kısaca bilgi sunmayı hedeflemektedir. Özelde ise, turizm açısından böylesine önemli ve katma değer oluşturabilecek bir konuda ülkemizde son yirmi yılda yapılan çalışmaları bir araya toplayıp okuyucuya sunarak bir bakıma akademinin konuya verdiği (veya vermediği) önemi göstermeyi amaçlamaktadır.
Proceedings of the Asian Internet Engineering Conference, 2017
An accurate traffic matrix (TM) is essential for network design, management and optimization. Sof... more An accurate traffic matrix (TM) is essential for network design, management and optimization. Software-defined networking (SDN) provides flow level statistics with global centralized control which enables construction of more accurate traffic matrices. However, retrieving all the flow statistics can cause a very significant overhead in the system. In this work, we propose an inference framework which utilizes Kalman filtering to create an accurate and timely traffic matrix. In our scheme, only a small number of flow statistics are measured at a time, yet the estimate of the TM is highly accurate. Besides, we propose a switch selection strategy which aims to minimize the entropy of the estimate, that is to maximize the information obtained by the estimation. Using simulation-based experiments, we show that our framework provides a very accurate TM estimate compared to the one constructed by using all the flow statistics in the network.
2021 43rd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC), 2021
Continuous, non-invasive wearable measurement of metabolic biomarkers could provide vital insight... more Continuous, non-invasive wearable measurement of metabolic biomarkers could provide vital insight into patient condition for personalized health and wellness monitoring. We present our efforts towards developing a wearable solar-powered electrochemical platform for multimodal sweat based metabolic monitoring. This wrist-worn wearable system consists of a flexible photovoltaic cell connected to a circuit board containing ultra low power circuitry for sensor data collection, energy harvesting, and wireless data transmission, all integrated into an elastic fabric wristband. The system continuously samples amperometric, potentiometric, temperature, and motion data and wirelessly transmits these to a data aggregator. The full wearable system is 7.5 cm long and 5 cm in diameter, weighs 22 grams, and can run directly from harvested light energy. Relatively low levels of light such as residential lighting (∼200 lux) are sufficient for continuous operation of the system. Excess harvested energy is stored in a small 37 mWh lithium polymer battery. The battery can be charged in ∼14 minutes under full sunlight and can power the system for ∼8 days when fully charged. The system has an average power consumption of 176 µW. The solar-harvesting performance of the system was characterized in a variety of lighting conditions, and the amperometric and potentiometric electrochemical capabilities of the system were validated in vitro. Clinical relevance-The presented solar-powered wearable system enables continuous wireless multi-modal electrochemical monitoring for uninterrupted sensing of metabolic biomarkers in sweat while harvesting energy from indoor lighting or sunlight.
Current treatment plans for chronic respiratory diseases are limited to single point measurements... more Current treatment plans for chronic respiratory diseases are limited to single point measurements obtained in the regulated environment of a clinic. Thus, the development of a continual health and environmental monitoring system would allow for a better understanding of how external factors are affecting the patient’s respiratory condition and would shift healthcare into a preventative rather than a reactive system that treats only the symptoms. In addition to the integrated electrocardiogram (ECG), ozone detector, three-axis accelerometer, and microphone, photoplethysmography (PPG) allows for a more complete physiological understanding of chronic respiratory conditions. Dual wavelength PPG allows for the measurement of respiratory rate, heart rate and arterial oxygenation (SpO2), and can be used in unison with ECG to provide an estimation of blood pressure via pulse transit time. Thus, the development of a robust, biologically compatible optical probe is crucial in achieving accura...
2008 IEEE 21st International Conference on Micro Electro Mechanical Systems, 2008
This paper reports the first direct control of insect flight by manipulating the wing motion via ... more This paper reports the first direct control of insect flight by manipulating the wing motion via microprobes and electronics introduced through the Early Metamorphosis Insertion Technology (EMIT). EMIT is a novel hybrid biology pathway for autonomous centimeter-scale robots that forms intimate electronic-tissue interfaces by placing electronics in the pupal stage of insect metamorphosis. Our new technology may enable insect cyborgs by realizing a reliable control interface between inserted microsystems and insect physiology. The design rules on the flexibility of the inserted microsystem and the investigation towards tissuemicroprobe biological and electrical compatibility are also presented.
Animal-assisted interventions (AAI) are a unique class of complementary medical treatments that c... more Animal-assisted interventions (AAI) are a unique class of complementary medical treatments that can improve a patient’s quality of life, both physically and psychologically. Part I of this two-paper systematic literature review series focused on the study methods and quantitative results of researchers in this field. We continue this in-depth review here in Part II by discussing the common theories associated with AAI in the context of cancer. Of all the factors at work in human-animal interactions, researchers explicitly cite compatible animal personality, physical touch, physical movement, distraction/entertainment, and increased human interaction as the mechanisms responsible for the positive clinical outcomes observed in AAI. In various combinations, these mechanisms group under broader theoretical frameworks that attempt to fully explain the AAI context as it relates to cancer care. The social support hypothesis and the conception of a human-animal bond are the most referenced ...
IEEE transactions on biomedical circuits and systems, Jun 8, 2017
A compressive sampling (CS) photoplethysmographic (PPG) readout with embedded feature extraction ... more A compressive sampling (CS) photoplethysmographic (PPG) readout with embedded feature extraction to estimate heart rate (HR) directly from compressively sampled data is presented. It integrates a low-power analog front end together with a digital back end to perform feature extraction to estimate the average HR over a 4 s interval directly from compressively sampled PPG data. The application-specified integrated circuit (ASIC) supports uniform sampling mode (1x compression) as well as CS modes with compression ratios of 8x, 10x, and 30x. CS is performed through nonuniformly subsampling the PPG signal, while feature extraction is performed using least square spectral fitting through Lomb-Scargle periodogram. The ASIC consumes 172 μW of power from a 1.2 V supply while reducing the relative LED driver power consumption by up to 30 times without significant loss of relevant information for accurate HR estimation.
We present an approach for global exploration and mapping of unknown environments using a swarm o... more We present an approach for global exploration and mapping of unknown environments using a swarm of cyborg insects, known as biobots, for emergency response scenarios under minimal sensing and localization constraints. We exploit natural stochastic motion models and controlled locomotion of biobots in conjunction with an aerial leader to explore and map a domain of interest. A sliding window strategy is adopted to construct local maps from coordinate free encounter information of the agents by means of local metric estimation. Robust topological features from these local representations are extracted using topological data analysis and a classification scheme. These maps are then merged into a global map which can be visualized using a graphical representation, that integrates geometric as well as topological features of the environment. Simulation and experimental results with biologically inspired robotic platform are presented to illustrate and verify the correctness of our approach, which provides building blocks for SLAM with biobotic insects.
Proceedings of the 12th International Conference on Advances in Computer Entertainment Technology, 2015
One of the challenges to working with canines is that whereas humans are primarily vocal communic... more One of the challenges to working with canines is that whereas humans are primarily vocal communicators, canines are primarily postural and behavioral communicators. It can take years to gain some level of proficiency at reading canine body language, even under the best of circumstances. In the case of guide dogs and visually-impaired handlers, this task is even more difficult. Luckily, new technology designed to help monitor canines may prove useful in helping handlers, especially those with visual impairments, to better understand and interpret what their working partners are feeling or saying. In prior work a lightweight , wearable, wireless physiological monitoring system was shown to be accurate for measuring canines' heart and respiratory rates [6]. In this paper, we consider the complementary problem of communicating physiological information to handlers. We introduce two nonvisual interfaces for monitoring a canine's heart and respiratory rates, an audio interface and a vibrotactile interface. We also present the results of two initial studies to evaluate the efficacy of the interfaces. In the first study we found that many participants were more confident in detecting changes in heart and respiratory rate using the audio interface, however most of the time they were just as accurate with the vibrotactile interface with only a slight increase in detection latency.
Proceedings of the 12th International Conference on Advances in Computer Entertainment Technology, 2015
Training animals is a process that requires a significant investment of time and energy on the pa... more Training animals is a process that requires a significant investment of time and energy on the part of the trainer. One of the most basic training tasks is to train dogs to perform postures on cue. While it might be easy for a human trainer to see when an animal has performed the desired posture, it is much more difficult for a computer to determine this. Most work in this area uses accelerometer and/or gyroscopic data to produce data from an animal's current state, but this has limitations. Take for example a normal standing posture. From an accelerometer's perspective, it closely resembles the "laying down" posture, but the posture can look very different if the animal is standing still, versus walking, versus running, and might look completely different from a "standing on incline" posture. A human trainer can instantly tell the difference between these postures and behaviors, but the process is much more difficult for a computer. This paper demonstrates several algorithms for recognizing canine postures, as well as a system for building a computational model of a canine's potential postures, based solely on skeletal measurements. Existing techniques use labeled data, which can be difficult to acquire. We contribute a new
In this paper, we present an approach for dynamic exploration and mapping of unknown environments... more In this paper, we present an approach for dynamic exploration and mapping of unknown environments using a swarm of biobotic sensing agents, with a stochastic natural motion model and a leading agent (e.g., an unmanned aerial vehicle). The proposed robust mapping technique constructs a topological map of the environment using only encounter information from the swarm. A sliding window strategy is adopted in conjunction with a topological mapping strategy based on local interactions among the swarm in a coordinate-free fashion to obtain local maps of the environment. These maps are then merged into a global topological map which can be visualized using a graphical representation that integrates geometric as well as topological feature of the environment. Localized robust topological features are extracted using tools from topological data analysis. Simulation results have been presented to illustrate and verify the correctness of our dynamic mapping algorithm.
Journal of visualized experiments : JoVE, Jan 12, 2014
Early Metamorphosis Insertion Technology (EMIT) is a novel methodology for integrating microfabri... more Early Metamorphosis Insertion Technology (EMIT) is a novel methodology for integrating microfabricated neuromuscular recording and actuation platforms on insects during their metamorphic development. Here, the implants are fused within the structure and function of the neuromuscular system as a result of metamorphic tissue remaking. The implants emerge with the insect where the development of tissue around the electronics during pupal development results in a bioelectrically and biomechanically enhanced tissue interface. This relatively more reliable and stable interface would be beneficial for many researchers exploring the neural basis of the insect locomotion with alleviated traumatic effects caused during adult stage insertions. In this article, we implant our electrodes into the indirect flight muscles of Manduca sexta. Located in the dorsal-thorax, these main flight powering dorsoventral and dorsolongitudinal muscles actuate the wings and supply the mechanical power for up and...
Newborns with critical health conditions are monitored in neonatal intensive care units (NICU). I... more Newborns with critical health conditions are monitored in neonatal intensive care units (NICU). In NICU, one of the most important problems that they face is the risk of brain injury. There is a need for continuous monitoring of newborn's brain function to prevent any potential brain injury. This type of monitoring should not interfere with intensive care of the newborn. Therefore, it should be non-invasive and portable. In this paper, a low-cost, battery operated, dual wavelength, continuous wave near infrared spectroscopy system for continuous bedside hemodynamic monitoring of neonatal brain is presented. The system has been designed to optimize SNR by optimizing the wavelength-multiplexing parameters with special emphasis on safety issues concerning burn injuries. SNR improvement by utilizing the entire dynamic range has been satisfied with modifications in analog circuitry. As a result, a shot-limited SNR of 67 dB has been achieved for 10 Hz temporal resolution. The system c...
Near infrared (NIR) light has been used widely to monitor important hemodynamic parameters in tis... more Near infrared (NIR) light has been used widely to monitor important hemodynamic parameters in tissue non-invasively. Pulse oximetry, near infrared spectroscopy, and diffuse optical tomography are examples of such NIR light-based applications. These and other similar applications employ either lasers or light emitting diodes (LED) as the source of the NIR light. Although the hazards of laser sources have been addressed in regulations, the risk of LED sources in such applications is still unknown. Temperature increase of the human skin caused by near infrared LED has been measured by means of in-vivo and in-vitro experiments. Effects of the conducted and radiated heat in the temperature increase have been analyzed separately. Elevations in skin temperature up to 10 degrees C have been observed. The effect of radiated heat due to NIR absorption is low--less than 0.5 degrees C--since emitted light power is comparable to the NIR part of sunlight. The conducted heat due to semiconductor j...
Proceedings of IEEE Ultrasonics Symposium ULTSYM-94, 1994
Lamb wave lenses with conical refracting surfaces are fabricated for use at 400 MHz and 1 GHz. Th... more Lamb wave lenses with conical refracting surfaces are fabricated for use at 400 MHz and 1 GHz. The conical surfaces are ground and polished with mechanical means and they are sufficiently smooth for the frequencies of interest. The wide bandwidth of transducers allow frequency tuning necessary for Lamb wave lenses. The fabricated lenses show the expected V (2) performance. At high frequencies the attenuation in the coupling medium can be very high, but due to the smaller wavelength the resolution is better and defocus distance can be reduced. Inherently higher leaky wave sensitivity of Lamb wave lens enables a good V (2) characterization ability a t higher frequencies as compared to the conventional spherical lens. Subsurface imaging with these Lamb wave lenses gives satisfactory results for layered structures. Chosen object has leaky wave modes within the angular coverage of the lens. The images exhibit a resolution close to the diffraction limit. Experimental V (2) curves obtained with these lenses along with images are presented
Uploads
Papers by Alper BOZKURT