Фотографія як вид мистецтва

Фотографія - це найдемократичніший вид мистецтва. Історія фотографії розпочалася близько 1816 року, коли Джезеф Нісефор Ньєпс винайшов спосіб отримання зображень предметів за допомогою камери-обскури. Першу в історії фотографію "вид з вікна" він отримав у 1826 році. Весь подальший розвиток фотографії відбувався в напрямі отримання більш досконалих знімків. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/3300

Feedback Control Goes Wireless: Guaranteed Stability over Low-power Multi-hop Networks

Closing feedback loops fast and over long distances is key to emerging applications; for example, robot motion control and swarm coordination require update intervals of tens of milliseconds. Low-power wireless technology is preferred for its low cost, small form factor, and flexibility, especially if the devices support multi-hop communication. So far, however, feedback control over wireless multi-hop networks has only been shown for update intervals on the order of seconds. This paper presents a wireless embedded system that tames imperfections impairing control performance (e.g., jitter and message loss), and a control design that exploits the essential properties of this system to provably guarantee closed-loop stability for physical processes with linear time-invariant dynamics. Using experiments on a cyber-physical testbed with 20 wireless nodes and multiple cart-pole systems, we are the first to demonstrate and evaluate feedback control and coordination over wireless multi-hop networks for update intervals of 20 to 50 milliseconds.Comment: Accepted final version to appear in: 10th ACM/IEEE International Conference on Cyber-Physical Systems (with CPS-IoT Week 2019) (ICCPS '19), April 16--18, 2019, Montreal, QC, Canad

Environmental Education After Sustainability : Hope in the Midst of Tragedy

In this article, I discuss the challenge posed to environmental education (EE; and education for sustainable development) by the thinkers who see the situation of the world as so severe that ‘sustainability’ is an outdated concept. My approach is interdisciplinary and I discuss especially the connections between EE and eco-psychology. Based on psychological research, I argue that the wide-scale unconscious anxiety, which people experience, should be taken very seriously in EE. My discussion thus contributes in a new kind of way to a long-standing key issue in EE, the gap between people’s values and the perceived action. Scholars of eco-anxiety have argued that instead of not caring, many people in fact care too much, and have to resort to psychological defenses of denial and disavowal. Thus, the question in EE is not anymore whether EE should deal with anxiety, for anxiety is already there. The prevailing attitude in EE writing is right in emphasizing positive matters and empowerment, but the relation between hope and optimism must be carefully thought about and a certain sense of tragedy must be included. Therefore, my article participates in the discussion about the role of ‘fear appeals’ in EE. My discussion is directed to anyone who wants to understand the reasons for inaction and the ways in which these may be overcome.Peer reviewe

Adaptive and Context-aware Service Discovery for the Internet of Things

This article was published in Lecture Notes in Computer Science [© Springer Verlag] and the definitive version is available at: http://dx.doi.org/10.1007/978-3-642-40316-3_4The Internet of Things (IoT) vision foresees a future Internet encompassing the realm of smart physical objects, which offer hosted functionality as services. The role of service discovery is crucial when providing application-level, end-to-end integration. In this paper, we propose trendy: a RESTful web services based Service Discovery protocol to tackle the challenges posed by constrained domains while offering the required interoperability. It provides a service selection technique to offer the appropriate service to the user application depending on the available context information of user and services. Furthermore, it employs a demand-based adaptive timer and caching mechanism to reduce the communication overhead and to decrease the service invocation delay. trendy’s grouping technique creates location-based teams of nodes to offer service composition. Our simulation results show that the employed techniques reduce the control packet overhead, service invocation delay and energy consumption. In addition, the grouping technique provides the foundation for group-based service mash-ups and localises control traffic to improve scalability

Online Checkpointing with Improved Worst-Case Guarantees

Abstract. In the online checkpointing problem, the task is to continuously maintain a set of k checkpoints that allow to rewind an ongoing computation faster than by a full restart. The only operation allowed is to remove an old checkpoint and to store the current state instead. Our aim are checkpoint placement strategies that minimize rewinding cost, i.e., such that at all times T when requested to rewind to some time t ≤ T the number of computation steps that need to be redone to get to t from a checkpoint before t is as small as possible. In particular, we want that the closest checkpoint earlier than t is not further away from t than pk times the ideal distance T/(k + 1), where pk is a small constant. Improving over earlier work showing 1 + 1/k ≤ pk ≤ 2, we show that pk can be chosen less than 2 uniformly for all k. More precisely, we show the uniform bound pk ≤ 1.7 for all k, and present algorithms with asymptotic performance pk ≤ 1.59 + o(1) valid for all k and pk ≤ ln(4) + o(1) ≤ 1.39+o(1) valid for k being a power of two. For small values of k, we show how to use a linear programming approach to compute good checkpointing algorithms. This gives performances of less than 1.53 for k ≤ 10. One the more theoretical side, we show the first lower bound that is asymptotically more than one, namely pk ≥ 1.30 − o(1). We also show that optimal algorithms (yielding the infimum performance) exist for all k.