Chemical transformation of pet waste through glycolysis

PET bottle grade material makes up a significant portion of the feedstock in plastics recycling. Theoretically, there are many end users however there are few applications for less purified grades of recycled PET. The current work is aiming to investigate the transformation of recycled PET into its chemical building blocks using glycolysis to produce unsaturated polyester resin. In this regard, PET waste has been collected from different sources, mainly, beverages and bottled water. Chemical transformation has been achieved through degrading glycolysis reaction with different glycols namely, propylene glycol, diethylene glycol, triethylene glycol and mixture of diethylene glycol with propylene glycol or triethylene glycol in equal amounts. The glycolized products have been converted into unsaturated polyester (UP) after the reaction with maleic anhydride. Finally, styrene was added as a crosslinker and the obtained UP has been characterized. Factors affecting the curing process of the obtained unsaturated polyester resin have been investigated.     

Synthesis of light weight recron fiber-reinforced sodium silicate based silica aerogel blankets at an ambient pressure for thermal protection

Journal of Porous Materials - In this work, for the sake of improving the performance of homogeneous and flexible silica aerogel blankets in practical applications, lightweight recron fibers were...     

Spatio-temporal composition of video objects: representation andquerying in video database systems

A key characteristic of video data is the associated spatial and temporal semantics. It is important that a video model models the characteristics of objects and their relationships in time and space. J.F. Allen's (1983) 13 temporal relationships are often used in formulating queries that contain the temporal relationships among video frames. For the spatial relationships, most of the approaches are based on projecting objects on a two or three-dimensional coordinate system. However, very few attempts have been made formally to represent the spatio-temporal relationships of objects contained in the video data and to formulate queries with spatio-temporal constraints. The purpose of the work is to design a model representation for the specification of the spatio-temporal relationships among objects in video sequences. The model describes the spatial relationships among objects for each frame in a given video scene and the temporal relationships (for this frame) of the temporal intervals measuring the duration of these spatial relationships. It also models the temporal composition of an object, which reflects the evolution of object's spatial relationships over the subsequent frames in the video scene and in the entire video sequence. Our model representation also provides an effective and expressive way for the complete and precise specification of distances among objects in digital video. This model is a basis for the annotation of raw video     

Spatio-Temporal Modeling in Video and Multimedia Geographic Information Systems

The geographic application domain includes important information such as design plans, record drawings, photographs, and video data records. The corresponding geographic information systems (GISs) should maintain a specific model for each geographic data modality such as geographic video model for video records. Real-time 3-D geographic information systems provide comprehensive interface to complex and dynamic databases and truly immersive capability for visualizing geographic data. In cases, where information about location of geographic objects is needed at different moments of time, a GIS should process video data that is directly manipulated and retrieved through representation of its spatio-temporal characteristics. In this context, the most advanced multimedia form—digital video, finds an efficient application in GIS for versatile specification of geographic data. In this paper, a model for spatial data evolving with time is introduced in the context of video data manipulation. We designed a model that represents the spatio-temporal continuum among geographic objects in geographic video sequences, or digital video. The model developed here was motivated by the requirements for manipulating, managing, and analyzing geographic data for the necessities of infrastructure management, urban and regional planning, hazard prevention and management, transportation networks, vehicles routing, etc. This model allows the important issues for GIS such as conditions of adjacency (what is next to what), containment (what is enclosed by what), and proximity (how close one geographic object is to another) to be determined. Our model describes the spatial relationships among objects for each key frame in a given video scene, and the temporal relationships of the temporal intervals measuring the validity duration of the spatial relationships spanning over the given key frame. One of the main GIS issues—distance estimation, is solved as quantitative metrics of geographic objects in digital video are easily and precisely specified. This model is a basis for annotation of raw video for subsequent use in geographic video databases and digital libraries that provide access to and efficient storage of large volume of geographic data.     

Maximizing Lifetime of Sensor Surveillance Systems

This paper addresses the maximal lifetime scheduling problem in sensor surveillance systems. Given a set of sensors and targets in an area, a sensor can watch only one target at a time, our task is to schedule sensors to watch targets and forward the sensed data to the base station, such that the lifetime of the surveillance system is maximized, where the lifetime is the duration that all targets are watched and all active sensors are connected to the base station. We propose an optimal solution to find the target-watching schedule for sensors that achieves the maximal lifetime. Our solution consists of three steps: 1) computing the maximal lifetime of the surveillance system and a workload matrix by using the linear programming technique; 2) decomposing the workload matrix into a sequence of schedule matrices that can achieve the maximal lifetime; and 3) determining the sensor surveillance trees based on the above obtained schedule matrices, which specify the active sensors and the routes to pass sensed data to the base station. This is the first time in the literature that the problem of maximizing lifetime of sensor surveillance systems has been formulated and the optimal solution has been found     

Modification of cellulose fibers with functionalized silanes: Effect of the fiber treatment on the mechanical performances of cellulose–thermoset composites

Unsaturated polyester and epoxy resin matrices were filled with silane‐treated cellulose fibers and the ensuing composites were tested in terms of mechanical properties before and after accelerated aging consisting of their immersion into water. The coupling agents used were γ‐aminopropyltriethoxysilane (APS), γ‐methacrylopropyltrimethoxysilane (MPS), hexadecytrimethoxysilane, and γ‐mercaptopropyltrimethoxysilane (MRPS) and those containing reactive functions capable of reacting at one end with the fibers and at the other with the matrix, namely, APS, MPS, and MRPS, were more efficient in improving the mechanical properties of the composites. The immersion into water induced a drastic loss of mechanical properties of the materials. The water uptake of the composites was also studied and showed that the silane treatment was poorly efficient in preventing cellulose from water absorption. The fracture surfaces were inspected by scanning electron microscopy, which confirmed the quality of the interface. These observations were in agreement with the results obtained from the dynamic mechanical characterization. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 974–984, 2005     

Using Logical Rings to Solve the Distributed Mutual Exclusion Problem with Fault Tolerance Issues

In this paper, we investigate distributed mutual exclusion algorithms and delineate the features of a new distributed mutual exclusion algorithm. The basis of the algorithm is the logical ring structure employed in token-based mutual exclusion algorithms. Specifically, there exists dynamic properties of the logical ring that, given certain restrictions regarding message traffic flow, passively give useful information about the location of the token. Effectively, the algorithm demonstrates a type of intelligent routing that identifies useful shortcuts in the routing of the token. The result is a reduction in the total number of messages exchanged prior to the execution of the critical section as compared to the algorithm proposed by Fu and Tzeng [3]. Furthermore, the algorithm allows for an increased degree of fairness in a lightly loaded system than that allowed by Fu and Tzeng's algorithm. The paper also addresses failure recovery issues.     

The CSMA/DM LAN protocol

We propose an extension of the classical CSMA/CD protocol that eliminates its three main drawbacks. The new protocol, called dual‐mode CSMA/CD (CSMA/DM), operates in two modes, light mode and heavy mode. The light mode of CSMA/DM is almost the same as the original CSMA/CD protocol and is primarily used when the LAN load is light. The heavy mode is a collision free mode and is applied when the LAN load is heavy. The proposed modification to CSMA/CD is minimal while performance gain is significant. CSMA/DM automatically switches between its two modes based on the observed LAN load. Under heavy mode, the monitor station in a CSMA/DM LAN allocates bandwidth to those busy stations without collisions. The newly added priority scheme in the heavy mode allows stations to reserve bandwidth for their high priority frames. Compared with the current collision‐free fast Ethernet and Gigabit Ethernet, CSMA/DM has the advantage of not needing any extra switches or hubs while maintaining comparable performance. Its priority scheme provides more flexibility on bandwidth distribution than in fast Ethernet and Gigabit Ethernet. It can also be easily adapted for high‐speed wireless LANs. More importantly, CSMA/DM should be a good alternative of the widely used CSMA/CA (collision avoidance) in mobile ad hoc networks (MANET) and sensor networks. Copyright © 2005 John Wiley & Sons, Ltd.     

Mode shaping of a graded-reflectivity-mirror unstable resonatorwith an intra-cavity phase element

A graded-reflectivity-mirror (GRM) unstable resonator with low output coupling is described, where a custom-made optical phase element is used inside the resonator to provide maximally flat output. The phase element removes the dip in the output beam by pre-compensating the internal Gaussian mode. An experiment is performed with a flashlamp-pumped Nd:YAG laser. The resonator's magnification (M) and the GRM's central reflectivity (R₀) are 2.3 and 0.7, respectively. The large dip in the center of the output is removed using the custom-made phase element. This resonator has the advantage over a conventional GRM unstable resonator of being suitable for lower-gain laser media. The gain required to overcome fundamental mode cavity losses for maximally flat output is decreased from 22.3 (for a conventional GRM resonator) to 4.3 (for the resonator containing the phase element). This reduction in required gain comes with essentially no loss to the resonator modal discrimination     

Mobile learning object authoring tool and management system for mobile ad hoc wireless networks

Mobile learning can augment formal education and bridge the gap between formal and informal education by creating extended learning communities using any digital technology in connected or infrastructure‐less environments. With the use of ad hoc networks and mobile authoring tools, we can now create an ‘on‐the‐fly’ learning scenario, where learners can create, share, and view content from their mobile devices without the need for server–client or infrastructure‐based liaisons. Mobile learning, however, is not just about sharing content or learning using mobile, wireless, and portable devices. Rather, it is learning across spatiotemporal contexts that enables learners to form knowledge and understanding in different scenarios. When facing limited resources stemming from the characteristics of mobility and wireless technologies, determining the best practices for content creation and delivery becomes a challenge. This paper describes the architecture of a mobile‐focused learning network designed so that learning tools, activities, contexts, and interactions are created as necessary over time and space while adhering to traditional learning object standards. Copyright © 2015 John Wiley & Sons, Ltd.