PET waste management in Pakistan through use of PET shreds as additive in backfill soil.

The management of waste plastic bottles is one of the major environmental challenges in the world. Plastic bottles are composed of polyethylene terephthalate (PET), which is non-biodegradable, resulting in environmental problems. Various studies have been carried out on the use of waste PET bottles in the form of custom-made strips as a stabilizer. However, no significant research has been carried out on the use of waste PET bottle shreds already available in the market. These shreds do not require any special technology or arrangement for bulk production. In this study, the shear strength of low plastic silty clay was improved using locally available PET shreds, and their prospective application in the backfill soil was investigated. Standard Proctor tests and direct shear tests were conducted on soil stabilized with three different sizes of plastic shreds (2 mm, 6 mm, and 10 mm) in four different percentages (1%, 3%, 5%, and 10%). Findings revealed that adding PET shreds in 1% content improves the shear strength characteristics. However, the shear strength parameters decrease with further increase in PET shred content. Therefore, PET shreds in 1% content can be added in backfill soil to improve its shear strength. Pakistan needs to construct 0.77 million housing units annually to keep up with its population growth. The statistics of seven major cities of Pakistan show that the PET waste management issue of Pakistan can be resolved by using PET shreds as a backfill additive in only 32% of the new houses required to be constructed.

Object Recognition in High-Resolution Indoor THz SAR Mapped Environment.

Synthetic aperture radar (SAR) at the terahertz (THz) spectrum has emerging short-range applications. In comparison to the microwave spectrum, the THz spectrum is limited in propagation range but benefits from high spatial resolution. The THz SAR is of significant interest for several applications which necessitate the mapping of indoor environments to support various endeavors such as rescue missions, map-assisted wireless communications, and household robotics. This paper addresses the augmentation of the high-resolution indoor mapped environment for object recognition, which includes detection, localization, and classification. Indoor object recognition is currently dominated by the usage of optical and infrared (IR) systems. However, it is not widely explored by radar technologies due to the limited spatial resolution at the most commonly used microwave frequencies. However, the THz spectrum provides a new paradigm of possible adaptation of object recognition in the radar domain by providing image quality in good compliance to optical/IR systems. In this paper, a multi-object indoor environment is foremost mapped at the THz spectrum ranging from 325 to 500 GHz in order to investigate the imaging in highly scattered environments and accordingly create a foundation for detection, localization, and classification. Furthermore, the extraction and clustering of features of the mapped environment are conducted for object detection and localization. Finally, the classification of detected objects is addressed with a supervised machine learning-based support vector machine (SVM) model.

Enhanced tunable plasmonic resonance in crumpled graphene resonators loaded with gate tunable metamaterials.

Graphene devices have been widely explored for photonic applications, as they serve as promising candidates for controlling light interactions resulting in extreme confinement and tunability of graphene plasmons. The ubiquitous presence of surface crumples in graphene, very less is known on how the crumples in graphene can affect surface plasmon resonance and its absorption properties. In this article, a novel approach based on the crumpled graphene is investigated to realize broadband tunability of plasmonic resonance through the mechanical reconfiguration of crumpled graphene resonators. The mechanical reconfiguration of graphene crumples combined with dual electrostatic gating (i.e. raising the Fermi level from 0.2-0.4 eV) of graphene serves as a tuning knob enabling broad spectral tunability of plasmonic resonance in the wavelength range of 14-24 µm. The crumpled region in the resonators exhibits an effective trapping potential where it extremely confines the surface plasmonic field on the surfaces of crumples providing localized surface plasmon resonance at the apices of these crumples. Finally, to achieve near-unity absorption >99% at the resonance wavelengths (17 µm and 22 µm) crumpled graphene resonators are loaded with four ring shaped metamaterials which result in the enhanced near-field intensity of ≈1.4×106. This study delivers insight into the tunability of crumpled graphene and their coupling mechanism by providing a new platform for the flexible and gate tunable graphene sensors at the infrared region.