skip to main content

Attention:

The NSF Public Access Repository (NSF-PAR) system and access will be unavailable from 11:00 PM ET on Thursday, June 13 until 2:00 AM ET on Friday, June 14 due to maintenance. We apologize for the inconvenience.


Search for: All records

Creators/Authors contains: "Mohamed, Ahmed"

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. Free, publicly-accessible full text available March 1, 2025
  2. Free, publicly-accessible full text available February 7, 2025
  3. This article investigates the feasibility of using regenerative energy from braking trains to charge electric buses in the context of New York City’s (NYC) subway and electric bus networks. A case study centered around NYC’s system has been performed to evaluate the benefits and challenges pertaining to the use of the preexisting subway network as a power supply for its new all-electric buses. The analysis shows that charging electric buses via the subway system during subway off-peak periods does not hinder regular train operation. In addition, having the charging electric buses connected to the third rail allows for more regenerative braking energy (RBE) to be recuperated, decreasing the energy wasted throughout the system. It was also found that including a wayside energy storage system (WESS) reduces the overall substation peak power consumption.

     
    more » « less
    Free, publicly-accessible full text available October 1, 2024
  4. Free, publicly-accessible full text available December 1, 2024
  5. Abstract

    This study relies on an experimental approach, utilising real data from multiple photovoltaic (PV) sites located in the US Northeaster region, to inspect how different inverter reactive and active power settings impact gird voltage regulation and inverter life expectancy. These voltage regulation schemes come at a cost for the operator. Data from different solar sites with inverters running at different reactive and active power settings were analysed to compare operational trade‐offs. These trade‐offs range from production losses to shortening the lifetime of the inverters. Voltage versus reactive power plots were analysed to show production losses, while the thermal analysis was used to correlate with the inverter life expectancy.

     
    more » « less
    Free, publicly-accessible full text available August 1, 2024
  6. Cryogenic infrared vibrational spectroscopy of D2-tagged cyanobenzoate (CBA) derivatives are obtained and analyzed to characterize the intrinsic spectroscopic responses of the -CO2‾ head group to its location on the ring in both the isolated anions and the cationic complexes with divalent metal ions, M2+ (M=Mg, Ca, Sr). The benzonitrile functionality establishes the different ring isomers (para, meta, ortho) according to the location of the carboxylate and provides an additional reporter on the molecular response to the proximal charge center. The aromatic carboxylates display slightly smaller shifts than those observed for a related aliphatic system upon metal ion complexation. Although the CBA anions display very similar band patterns for all three ring positions, upon complexation with metal ions, the ortho isomer yields dramatically different spectral responses in both the -CO2‾ moiety and the CN group. This behavior is traced to the emergence of a tridentate binding motif unique to the ortho isomer in which the metal ions bind to both the oxygen atoms of the carboxylate group and the N atom of the cyano group. In that configuration, the -CO2‾ moiety is oriented perpendicular to the phenyl ring, and the CN stretching fundamental is both strong and red-shifted relative to its behavior in the isolated neutral. The behaviors of the metal-bound ortho complexes occur in contrast to the usual blue shifts associated with “Lewis” type binding of metal ions end-on to -CN. The origins of these spectroscopic features are analyzed with the aid of electronic structure calculations, which also explore differences expected for complexation of monovalent cations to the ortho carboxylate. The resulting insights have implications for understanding the balance between electrostatic and steric interactions at metal binding sites in chemical and biological systems. 
    more » « less
  7. The mass deployment of energy storage and distributed energy resources has become a major goal across several states in the United States. However, the viability and reality of such a goal in New York City has been put in question as possible financial burdens and execution risks are still unclear, while policies and regulations are still not fully settled. This paper provides a foundational overview of the Lazard LCOS study with emphasis on forward states which have successfully implemented mass deployment of energy storage technologies. “Adders” are related to the practicality in deploying these systems in a highly regulated and densely populated urban area such as New York City. It also discusses details on the typical financial structure/incentives that support the policies and regulations that allow for achieving these clean energy goals. Furthermore, many states have begun to focus on alternative battery technologies rather than just Li-ion, and as such, New York State is following suit. Utilizing several similar works that have begun to touch on these considerations individually and various accredited resources, this paper discusses “adders” for New York City (and New York State as a whole) as they develop similar approaches that are unique to them and offers helpful conclusions and recommendations to achieve their deployment goals. 
    more » « less
  8. New York City’s food distribution system is among the largest in the United States. Food is transported by trucks from twelve major distribution centers to the city’s point-of-sale locations. Trucks consume large amounts of energy and contribute to large amounts of greenhouse gas emissions. Therefore, there is interest to increase the efficiency of New York City’s food distribution system. The Gowanus district in New York City is undergoing rezoning from an industrial zone to a mix residential and industrial zone. It serves as a living lab to test new initiatives, policies, and new infrastructure for electric vehicles. We analyze the impact of electrification of food-distribution trucks on greenhouse gas emissions and electricity demand in this paper. However, such analysis faces the challenges of accessing available and granular data, modeling of demands and deliveries that incorporate logistics and inventory management of different types of food retail stores, delivery route selection, and delivery schedule to optimize food distribution. We propose a framework to estimate truck routes for food delivery at a district level. We model the schedule of food delivery from a distribution center to retail stores as a vehicle routing problem using an optimization solver. Our case study shows that diesel trucks consume 300% more energy than electric trucks and generate 40% more greenhouse gases than diesel trucks for food distribution in the Gowanus district. 
    more » « less